diff --git a/setup.py b/setup.py
index 4f1309b8..ecef35ac 100644
--- a/setup.py
+++ b/setup.py
@@ -52,7 +52,7 @@
             "twine",
             "jsonschema==3.2.0",
             "xmlschema==3.3.1",
-            "aas-core-meta@git+https://github.com/aas-core-works/aas-core-meta@6d5411b#egg=aas-core-meta",
+            "aas-core-meta@git+https://github.com/aas-core-works/aas-core-meta@31d6afd#egg=aas-core-meta",
             "ssort==0.12.3",
         ]
     },
diff --git a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/enhancing.hpp b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/enhancing.hpp
index fb9d81d2..5b7c79a1 100644
--- a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/enhancing.hpp
+++ b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/enhancing.hpp
@@ -7118,22 +7118,16 @@ class EnhancedEmbeddedDataSpecification
     instance_->set_data_specification_content(value);
   }
 
-  const common::optional<
-    std::shared_ptr<types::IReference>
-  >& data_specification() const override {
+  const std::shared_ptr<types::IReference>& data_specification() const override {
     return instance_->data_specification();
   }
 
-  common::optional<
-    std::shared_ptr<types::IReference>
-  >& mutable_data_specification() override {
+  std::shared_ptr<types::IReference>& mutable_data_specification() override {
     return instance_->mutable_data_specification();
   }
 
   void set_data_specification(
-    common::optional<
-      std::shared_ptr<types::IReference>
-    > value
+    std::shared_ptr<types::IReference> value
   ) override {
     instance_->set_data_specification(value);
   }
@@ -13537,26 +13531,12 @@ std::shared_ptr<types::IEmbeddedDataSpecification> WrapEmbeddedDataSpecification
     )
   );
 
-  if (that->data_specification().has_value()) {
-    const std::shared_ptr<types::IReference>& value(
-      that->data_specification().value()
-    );
-
-    std::shared_ptr<
-      types::IReference
-    > wrapped(
-      Wrap<E>(
-        value,
-        factory
-      )
-    );
-
-    that->set_data_specification(
-      common::make_optional(
-        std::move(wrapped)
-      )
-    );
-  }
+  that->set_data_specification(
+    Wrap<E>(
+      that->data_specification(),
+      factory
+    )
+  );
 
   std::shared_ptr<E> enh(
     factory(that)
diff --git a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/iteration.cpp b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/iteration.cpp
index d16d0426..8e652f4f 100644
--- a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/iteration.cpp
+++ b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/iteration.cpp
@@ -11313,15 +11313,10 @@ void IteratorOverEmbeddedDataSpecification::Execute() {
       }
 
       case 1: {
-        if (!(casted_->data_specification().has_value())) {
-          state_ = 2;
-          continue;
-        }
-
         property_ = Property::kDataSpecification;
         item_ = std::move(
           std::static_pointer_cast<types::IClass>(
-            *(casted_->data_specification())
+            casted_->data_specification()
           )
         );
         ++index_;
diff --git a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/jsonization.cpp b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/jsonization.cpp
index 83663d2a..8b04abd1 100644
--- a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/jsonization.cpp
+++ b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/jsonization.cpp
@@ -23597,6 +23597,18 @@ std::pair<
     );
   }
 
+  if (!json.contains("dataSpecification")) {
+    return std::make_pair<
+      common::optional<std::shared_ptr<types::IEmbeddedDataSpecification> >,
+      common::optional<DeserializationError>
+    >(
+      common::nullopt,
+      common::make_optional<DeserializationError>(
+        L"The required property dataSpecification is missing"
+      )
+    );
+  }
+
   // endregion Check required properties
 
   // region Initialization
@@ -23605,9 +23617,7 @@ std::pair<
 
   common::optional<std::shared_ptr<types::IDataSpecificationContent> > the_data_specification_content;
 
-  common::optional<
-    std::shared_ptr<types::IReference>
-  > the_data_specification;
+  common::optional<std::shared_ptr<types::IReference> > the_data_specification;
 
   // endregion Initialization
 
@@ -23641,30 +23651,28 @@ std::pair<
 
   // region De-serialize dataSpecification
 
-  if (json.contains("dataSpecification")) {
-    std::tie(
-      the_data_specification,
-      error
-    ) = DeserializeReference(
-      json["dataSpecification"],
-      additional_properties
-    );
+  std::tie(
+    the_data_specification,
+    error
+  ) = DeserializeReference(
+    json["dataSpecification"],
+    additional_properties
+  );
 
-    if (error.has_value()) {
-      error->path.segments.emplace_front(
-        common::make_unique<PropertySegment>(
-          L"dataSpecification"
-        )
-      );
+  if (error.has_value()) {
+    error->path.segments.emplace_front(
+      common::make_unique<PropertySegment>(
+        L"dataSpecification"
+      )
+    );
 
-      return std::make_pair<
-        common::optional<std::shared_ptr<types::IEmbeddedDataSpecification> >,
-        common::optional<DeserializationError>
-      >(
-        common::nullopt,
-        std::move(error)
-      );
-    }
+    return std::make_pair<
+      common::optional<std::shared_ptr<types::IEmbeddedDataSpecification> >,
+      common::optional<DeserializationError>
+    >(
+      common::nullopt,
+      std::move(error)
+    );
   }
 
   // endregion De-serialize dataSpecification
@@ -23678,7 +23686,7 @@ std::pair<
       // upcast.
       new types::EmbeddedDataSpecification(
         std::move(*the_data_specification_content),
-        std::move(the_data_specification)
+        std::move(*the_data_specification)
       )
     ),
     common::nullopt
@@ -36939,40 +36947,33 @@ std::pair<
     *json_data_specification_content
   );
 
-  const common::optional<
-    std::shared_ptr<types::IReference>
-  >& maybe_data_specification(
-    that.data_specification()
+  common::optional<nlohmann::json> json_data_specification;
+  std::tie(
+    json_data_specification,
+    error
+  ) = SerializeIClass(
+    *that.data_specification()
   );
-  if (maybe_data_specification.has_value()) {
-    common::optional<nlohmann::json> json_data_specification;
-    std::tie(
-      json_data_specification,
-      error
-    ) = SerializeIClass(
-      **maybe_data_specification
+  if (error.has_value()) {
+    error->path.segments.emplace_front(
+      common::make_unique<iteration::PropertySegment>(
+        iteration::Property::kDataSpecification
+      )
     );
-    if (error.has_value()) {
-      error->path.segments.emplace_front(
-        common::make_unique<iteration::PropertySegment>(
-          iteration::Property::kDataSpecification
-        )
-      );
-
-      return std::make_pair<
-        common::optional<nlohmann::json>,
-        common::optional<SerializationError>
-      >(
-        common::nullopt,
-        std::move(error)
-      );
-    }
 
-    result["dataSpecification"] = std::move(
-      *json_data_specification
+    return std::make_pair<
+      common::optional<nlohmann::json>,
+      common::optional<SerializationError>
+    >(
+      common::nullopt,
+      std::move(error)
     );
   }
 
+  result["dataSpecification"] = std::move(
+    *json_data_specification
+  );
+
   return std::make_pair<
     common::optional<nlohmann::json>,
     common::optional<SerializationError>
diff --git a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/types.cpp b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/types.cpp
index 36e1f1da..87663afe 100644
--- a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/types.cpp
+++ b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/types.cpp
@@ -6912,9 +6912,7 @@ void Environment::set_concept_descriptions(
 
 EmbeddedDataSpecification::EmbeddedDataSpecification(
   std::shared_ptr<IDataSpecificationContent> data_specification_content,
-  common::optional<
-    std::shared_ptr<IReference>
-  > data_specification
+  std::shared_ptr<IReference> data_specification
 ) {
   data_specification_content_ = std::move(data_specification_content);
 
@@ -6939,22 +6937,16 @@ void EmbeddedDataSpecification::set_data_specification_content(
   data_specification_content_ = value;
 }
 
-const common::optional<
-  std::shared_ptr<IReference>
->& EmbeddedDataSpecification::data_specification() const {
+const std::shared_ptr<IReference>& EmbeddedDataSpecification::data_specification() const {
   return data_specification_;
 }
 
-common::optional<
-  std::shared_ptr<IReference>
->& EmbeddedDataSpecification::mutable_data_specification() {
+std::shared_ptr<IReference>& EmbeddedDataSpecification::mutable_data_specification() {
   return data_specification_;
 }
 
 void EmbeddedDataSpecification::set_data_specification(
-  common::optional<
-    std::shared_ptr<IReference>
-  > value
+  std::shared_ptr<IReference> value
 ) {
   data_specification_ = value;
 }
diff --git a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/types.hpp b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/types.hpp
index 37336777..b54c0e70 100644
--- a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/types.hpp
+++ b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/types.hpp
@@ -2942,18 +2942,12 @@ class IEmbeddedDataSpecification
   ///@{
   /// \brief Reference to the data specification
 
-  virtual const common::optional<
-    std::shared_ptr<IReference>
-  >& data_specification() const = 0;
+  virtual const std::shared_ptr<IReference>& data_specification() const = 0;
 
-  virtual common::optional<
-    std::shared_ptr<IReference>
-  >& mutable_data_specification() = 0;
+  virtual std::shared_ptr<IReference>& mutable_data_specification() = 0;
 
   virtual void set_data_specification(
-    common::optional<
-      std::shared_ptr<IReference>
-    > value
+    std::shared_ptr<IReference> value
   ) = 0;
 
   ///@}
@@ -10275,11 +10269,9 @@ class Environment
 class EmbeddedDataSpecification
     : public IEmbeddedDataSpecification {
  public:
-  explicit EmbeddedDataSpecification(
+  EmbeddedDataSpecification(
     std::shared_ptr<IDataSpecificationContent> data_specification_content,
-    common::optional<
-      std::shared_ptr<IReference>
-    > data_specification = common::nullopt
+    std::shared_ptr<IReference> data_specification
   );
 
   ModelType model_type() const override;
@@ -10298,18 +10290,12 @@ class EmbeddedDataSpecification
 
   // region Get and set data_specification_
 
-  const common::optional<
-    std::shared_ptr<IReference>
-  >& data_specification() const override;
+  const std::shared_ptr<IReference>& data_specification() const override;
 
-  common::optional<
-    std::shared_ptr<IReference>
-  >& mutable_data_specification() override;
+  std::shared_ptr<IReference>& mutable_data_specification() override;
 
   void set_data_specification(
-    common::optional<
-      std::shared_ptr<IReference>
-    > value
+    std::shared_ptr<IReference> value
   ) override;
 
   // endregion
@@ -10319,9 +10305,7 @@ class EmbeddedDataSpecification
  private:
   std::shared_ptr<IDataSpecificationContent> data_specification_content_;
 
-  common::optional<
-    std::shared_ptr<IReference>
-  > data_specification_;
+  std::shared_ptr<IReference> data_specification_;
 };
 
 class LevelType
diff --git a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/verification.cpp b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/verification.cpp
index 6da0a6f0..017a0b99 100644
--- a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/verification.cpp
+++ b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/verification.cpp
@@ -5421,33 +5421,12 @@ void OfPathType::Execute() {
       }
 
       case 3: {
-        if (
-          MatchesRfc8089Path(
-            (*value_)
-          )
-        ) {
-          state_ = 4;
-          continue;
-        }
-
-        error_ = common::make_unique<Error>(
-          L"The value must represent a valid file URI scheme according "
-          L"to RFC 8089."
-        );
-        // No path is prepended as the error refers to the value itself.
-        ++index_;
-
-        state_ = 4;
-        return;
-      }
-
-      case 4: {
         done_ = true;
         error_ = nullptr;
         index_ = -1;
 
         // We invalidate the state since we reached the end of the routine.
-        state_ = 5;
+        state_ = 4;
         return;
       }
 
@@ -24262,7 +24241,7 @@ void OfDataSpecificationIec61360::Execute() {
         }
 
         error_ = common::make_unique<Error>(
-          L"Constraint AASc-002: preferred name shall be provided at "
+          L"Constraint AASc-3a-002: preferred name shall be provided at "
           L"least in English."
         );
         // No path is prepended as the error refers to the instance itself.
diff --git a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/visitation.cpp b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/visitation.cpp
index 953e5fb9..3554ad4c 100644
--- a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/visitation.cpp
+++ b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/visitation.cpp
@@ -3095,18 +3095,10 @@ void PassThroughVisitor::VisitEmbeddedDataSpecification(
     that->mutable_data_specification_content()
   );
 
-  // region mutable_data_specification
-  const common::optional<
-    std::shared_ptr<types::IReference>
-  >& maybe_data_specification(
+  // mutable_data_specification
+  Visit(
     that->mutable_data_specification()
   );
-  if (maybe_data_specification.has_value()) {
-    Visit(
-      maybe_data_specification.value()
-    );
-  }
-  // endregion
 }
 
 void PassThroughVisitor::VisitLevelType(
diff --git a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/xmlization.cpp b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/xmlization.cpp
index 9dd7593a..ef66436f 100644
--- a/test_data/cpp/test_main/aas_core_meta.v3/expected_output/xmlization.cpp
+++ b/test_data/cpp/test_main/aas_core_meta.v3/expected_output/xmlization.cpp
@@ -31507,9 +31507,7 @@ std::pair<
 
   common::optional<std::shared_ptr<types::IDataSpecificationContent> > the_data_specification_content;
 
-  common::optional<
-    std::shared_ptr<types::IReference>
-  > the_data_specification;
+  common::optional<std::shared_ptr<types::IReference> > the_data_specification;
 
   // endregion Initialization
 
@@ -31694,6 +31692,14 @@ std::pair<
     );
   }
 
+  if (!the_data_specification.has_value()) {
+    return NoInstanceAndDeserializationErrorWithCause<
+      std::shared_ptr<T>
+    >(
+      L"The required property dataSpecification is missing"
+    );
+  }
+
   // endregion Check required properties
 
   return std::make_pair(
@@ -31705,7 +31711,7 @@ std::pair<
       // upcast.
       new types::EmbeddedDataSpecification(
         std::move(*the_data_specification_content),
-        std::move(the_data_specification)
+        std::move(*the_data_specification)
       )
     ),
     common::nullopt
@@ -53775,46 +53781,41 @@ common::optional<SerializationError> SerializeEmbeddedDataSpecificationAsSequenc
     return error;
   }
 
-  const auto& maybe_data_specification(
+  const std::shared_ptr<types::IReference>& the_data_specification(
     that.data_specification()
   );
-  if (maybe_data_specification.has_value()) {
-    const std::shared_ptr<types::IReference>& the_data_specification(
-      *maybe_data_specification
-    );
-    writer.StartElement(
-      "dataSpecification"
-    );
-    if (writer.error().has_value()) {
-      return writer.move_error();
-    }
-    error = SerializeReferenceAsSequence(
-      *the_data_specification,
-      writer
+  writer.StartElement(
+    "dataSpecification"
+  );
+  if (writer.error().has_value()) {
+    return writer.move_error();
+  }
+  error = SerializeReferenceAsSequence(
+    *the_data_specification,
+    writer
+  );
+  if (error.has_value()) {
+    error->path.segments.emplace_front(
+      common::make_unique<iteration::PropertySegment>(
+        iteration::Property::kDataSpecification
+      )
     );
-    if (error.has_value()) {
-      error->path.segments.emplace_front(
-        common::make_unique<iteration::PropertySegment>(
-          iteration::Property::kDataSpecification
-        )
-      );
 
-      return error;
-    }
-    writer.StopElement(
-      "dataSpecification"
-    );
-    if (writer.error().has_value()) {
-      error = writer.move_error();
+    return error;
+  }
+  writer.StopElement(
+    "dataSpecification"
+  );
+  if (writer.error().has_value()) {
+    error = writer.move_error();
 
-      error->path.segments.emplace_front(
-        common::make_unique<iteration::PropertySegment>(
-          iteration::Property::kDataSpecification
-        )
-      );
+    error->path.segments.emplace_front(
+      common::make_unique<iteration::PropertySegment>(
+        iteration::Property::kDataSpecification
+      )
+    );
 
-      return error;
-    }
+    return error;
   }
 
   writer.Finish();
diff --git a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/copying.cs b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/copying.cs
index c2fed0e4..ef6cb8aa 100644
--- a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/copying.cs
+++ b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/copying.cs
@@ -2457,9 +2457,7 @@ Aas.IEmbeddedDataSpecification that
             {
                 return new Aas.EmbeddedDataSpecification(
                     Deep(that.DataSpecificationContent),
-                    (that.DataSpecification != null)
-                        ? Deep(that.DataSpecification)
-                        : null
+                    Deep(that.DataSpecification)
                 );
             }
 
diff --git a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/enhancing.cs b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/enhancing.cs
index 34c63df1..eae4a3e0 100644
--- a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/enhancing.cs
+++ b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/enhancing.cs
@@ -3719,7 +3719,7 @@ public IDataSpecificationContent DataSpecificationContent
                 set => _instance.DataSpecificationContent = value;
             }
 
-            public IReference? DataSpecification
+            public IReference DataSpecification
             {
                 get => _instance.DataSpecification;
                 set => _instance.DataSpecification = value;
@@ -7660,19 +7660,16 @@ transformedDataSpecificationContent as Aas.IDataSpecificationContent
                 );
                 that.DataSpecificationContent = castedDataSpecificationContent;
 
-                if (that.DataSpecification != null)
-                {
-                    var transformedDataSpecification = Transform(
-                        that.DataSpecification
-                    );
-                    var castedDataSpecification = (
-                        transformedDataSpecification as Aas.IReference
-                    ) ?? throw new System.InvalidOperationException(
-                        "Expected the transformed value to be a IReference, " +
-                        $"but got: {transformedDataSpecification}"
-                    );
-                    that.DataSpecification = castedDataSpecification;
-                }
+                var transformedDataSpecification = Transform(
+                    that.DataSpecification
+                );
+                var castedDataSpecification = (
+                    transformedDataSpecification as Aas.IReference
+                ) ?? throw new System.InvalidOperationException(
+                    "Expected the transformed value to be a IReference, " +
+                    $"but got: {transformedDataSpecification}"
+                );
+                that.DataSpecification = castedDataSpecification;
 
                 var enhancement = _enhancementFactory(that);
                 return (enhancement == null)
diff --git a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/jsonization.cs b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/jsonization.cs
index 2fa54697..5247df71 100644
--- a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/jsonization.cs
+++ b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/jsonization.cs
@@ -13875,11 +13875,20 @@ internal static class DeserializeImplementation
                     return null;
                 }
 
+                if (theDataSpecification == null)
+                {
+                    error = new Reporting.Error(
+                        "Required property \"dataSpecification\" is missing");
+                    return null;
+                }
+
                 return new Aas.EmbeddedDataSpecification(
                     theDataSpecificationContent
                          ?? throw new System.InvalidOperationException(
                             "Unexpected null, had to be handled before"),
-                    theDataSpecification);
+                    theDataSpecification
+                         ?? throw new System.InvalidOperationException(
+                            "Unexpected null, had to be handled before"));
             }  // internal static EmbeddedDataSpecificationFrom
 
             /// <summary>
@@ -19140,11 +19149,8 @@ Aas.IEmbeddedDataSpecification that
                 result["dataSpecificationContent"] = Transform(
                     that.DataSpecificationContent);
 
-                if (that.DataSpecification != null)
-                {
-                    result["dataSpecification"] = Transform(
-                        that.DataSpecification);
-                }
+                result["dataSpecification"] = Transform(
+                    that.DataSpecification);
 
                 return result;
             }
diff --git a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/types.cs b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/types.cs
index 888fb754..f5777508 100644
--- a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/types.cs
+++ b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/types.cs
@@ -11894,7 +11894,7 @@ public interface IEmbeddedDataSpecification : IClass
         /// <summary>
         /// Reference to the data specification
         /// </summary>
-        public IReference? DataSpecification { get; set; }
+        public IReference DataSpecification { get; set; }
     }
 
     /// <summary>
@@ -11910,7 +11910,7 @@ public class EmbeddedDataSpecification : IEmbeddedDataSpecification
         /// <summary>
         /// Reference to the data specification
         /// </summary>
-        public IReference? DataSpecification { get; set; }
+        public IReference DataSpecification { get; set; }
 
         /// <summary>
         /// Iterate over all the class instances referenced from this instance
@@ -11920,10 +11920,7 @@ public IEnumerable<IClass> DescendOnce()
         {
             yield return DataSpecificationContent;
 
-            if (DataSpecification != null)
-            {
-                yield return DataSpecification;
-            }
+            yield return DataSpecification;
         }
 
         /// <summary>
@@ -11939,15 +11936,12 @@ public IEnumerable<IClass> Descend()
                 yield return anItem;
             }
 
-            if (DataSpecification != null)
-            {
-                yield return DataSpecification;
+            yield return DataSpecification;
 
-                // Recurse
-                foreach (var anItem in DataSpecification.Descend())
-                {
-                    yield return anItem;
-                }
+            // Recurse
+            foreach (var anItem in DataSpecification.Descend())
+            {
+                yield return anItem;
             }
         }
 
@@ -11993,7 +11987,7 @@ public T Transform<TContext, T>(
 
         public EmbeddedDataSpecification(
             IDataSpecificationContent dataSpecificationContent,
-            IReference? dataSpecification = null)
+            IReference dataSpecification)
         {
             DataSpecificationContent = dataSpecificationContent;
             DataSpecification = dataSpecification;
diff --git a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/verification.cs b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/verification.cs
index 05cc3418..1d34168b 100644
--- a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/verification.cs
+++ b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/verification.cs
@@ -9119,15 +9119,12 @@ Aas.IEmbeddedDataSpecification that
                     yield return error;
                 }
 
-                if (that.DataSpecification != null)
+                foreach (var error in Verification.Verify(that.DataSpecification))
                 {
-                    foreach (var error in Verification.Verify(that.DataSpecification))
-                    {
-                        error.PrependSegment(
-                            new Reporting.NameSegment(
-                                "dataSpecification"));
-                        yield return error;
-                    }
+                    error.PrependSegment(
+                        new Reporting.NameSegment(
+                            "dataSpecification"));
+                    yield return error;
                 }
             }
 
@@ -9373,7 +9370,7 @@ Aas.IDataSpecificationIec61360 that
                 {
                     yield return new Reporting.Error(
                         "Invariant violated:\n" +
-                        "Constraint AASc-002: preferred name shall be provided at " +
+                        "Constraint AASc-3a-002: preferred name shall be provided at " +
                         "least in English.");
                 }
 
@@ -9934,14 +9931,6 @@ var error in Verification.VerifyNonEmptyXmlSerializableString(
                     "Invariant violated:\n" +
                     "Identifier shall have a maximum length of 2000 characters.");
             }
-
-            if (!Verification.MatchesRfc8089Path(that))
-            {
-                yield return new Reporting.Error(
-                    "Invariant violated:\n" +
-                    "The value must represent a valid file URI scheme according " +
-                    "to RFC 8089.");
-            }
         }
 
         /// <summary>
diff --git a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/xmlization.cs b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/xmlization.cs
index c343b5d3..8f4ce6f9 100644
--- a/test_data/csharp/test_main/aas_core_meta.v3/expected_output/xmlization.cs
+++ b/test_data/csharp/test_main/aas_core_meta.v3/expected_output/xmlization.cs
@@ -17133,11 +17133,21 @@ out Reporting.Error? error
                     return null;
                 }
 
+                if (theDataSpecification == null)
+                {
+                    error = new Reporting.Error(
+                        "The required property DataSpecification has not been given " +
+                        "in the XML representation of an instance of class EmbeddedDataSpecification");
+                    return null;
+                }
+
                 return new Aas.EmbeddedDataSpecification(
                     theDataSpecificationContent
                          ?? throw new System.InvalidOperationException(
                             "Unexpected null, had to be handled before"),
-                    theDataSpecification);
+                    theDataSpecification
+                         ?? throw new System.InvalidOperationException(
+                            "Unexpected null, had to be handled before"));
             }  // internal static Aas.EmbeddedDataSpecification? EmbeddedDataSpecificationFromSequence
 
             /// <summary>
@@ -25822,18 +25832,15 @@ private void EmbeddedDataSpecificationToSequence(
 
                 writer.WriteEndElement();
 
-                if (that.DataSpecification != null)
-                {
-                    writer.WriteStartElement(
-                        "dataSpecification",
-                        NS);
+                writer.WriteStartElement(
+                    "dataSpecification",
+                    NS);
 
-                    this.ReferenceToSequence(
-                        that.DataSpecification,
-                        writer);
+                this.ReferenceToSequence(
+                    that.DataSpecification,
+                    writer);
 
-                    writer.WriteEndElement();
-                }
+                writer.WriteEndElement();
             }  // private void EmbeddedDataSpecificationToSequence
 
             public override void VisitEmbeddedDataSpecification(
diff --git a/test_data/golang/test_main/aas_core_meta.v3/expected_output/enhancing/enhancing.go b/test_data/golang/test_main/aas_core_meta.v3/expected_output/enhancing/enhancing.go
index aa14ad87..6e92c85b 100644
--- a/test_data/golang/test_main/aas_core_meta.v3/expected_output/enhancing/enhancing.go
+++ b/test_data/golang/test_main/aas_core_meta.v3/expected_output/enhancing/enhancing.go
@@ -6207,14 +6207,12 @@ func wrapEmbeddedDataSpecification[E any](
 	)
 
 	theDataSpecification := that.DataSpecification()
-	if theDataSpecification != nil {
-		that.SetDataSpecification(
-			Wrap[E](
-				theDataSpecification,
-				factory,
-			).(aastypes.IReference),
-		)
-	}
+	that.SetDataSpecification(
+		Wrap[E](
+			theDataSpecification,
+			factory,
+		).(aastypes.IReference),
+	)
 
 	return
 }
diff --git a/test_data/golang/test_main/aas_core_meta.v3/expected_output/jsonization/jsonization.go b/test_data/golang/test_main/aas_core_meta.v3/expected_output/jsonization/jsonization.go
index aa7b14a9..8ac392c9 100644
--- a/test_data/golang/test_main/aas_core_meta.v3/expected_output/jsonization/jsonization.go
+++ b/test_data/golang/test_main/aas_core_meta.v3/expected_output/jsonization/jsonization.go
@@ -13131,6 +13131,7 @@ func embeddedDataSpecificationFromMapWithoutDispatch(
 	var theDataSpecification aastypes.IReference
 
 	foundDataSpecificationContent := false
+	foundDataSpecification := false
 
 	for k, v := range m {
 		switch k {
@@ -13164,6 +13165,7 @@ func embeddedDataSpecificationFromMapWithoutDispatch(
 				}
 				return
 			}
+			foundDataSpecification = true
 
 		default:
 			err = newDeserializationError(
@@ -13183,10 +13185,15 @@ func embeddedDataSpecificationFromMapWithoutDispatch(
 		return
 	}
 
+	if !foundDataSpecification {
+		err = newDeserializationError(
+			"The required property 'dataSpecification' is missing",
+		)
+		return
+	}
+
 	result = aastypes.NewEmbeddedDataSpecification(
 		theDataSpecificationContent,
-	)
-	result.SetDataSpecification(
 		theDataSpecification,
 	)
 
@@ -21216,24 +21223,22 @@ func embeddedDataSpecificationToMap(
 	}
 	result["dataSpecificationContent"] = jsonableDataSpecificationContent
 
-	if that.DataSpecification() != nil {
-		var jsonableDataSpecification interface{}
-		jsonableDataSpecification, err = ToJsonable(
-			that.DataSpecification(),
-		)
-		if err != nil {
-			if seriaErr, ok := err.(*SerializationError); ok {
-				seriaErr.Path.PrependName(
-					&aasreporting.NameSegment{
-						Name: "DataSpecification()",
-					},
-				)
-			}
-
-			return
+	var jsonableDataSpecification interface{}
+	jsonableDataSpecification, err = ToJsonable(
+		that.DataSpecification(),
+	)
+	if err != nil {
+		if seriaErr, ok := err.(*SerializationError); ok {
+			seriaErr.Path.PrependName(
+				&aasreporting.NameSegment{
+					Name: "DataSpecification()",
+				},
+			)
 		}
-		result["dataSpecification"] = jsonableDataSpecification
+
+		return
 	}
+	result["dataSpecification"] = jsonableDataSpecification
 
 	return
 }
diff --git a/test_data/golang/test_main/aas_core_meta.v3/expected_output/types/types.go b/test_data/golang/test_main/aas_core_meta.v3/expected_output/types/types.go
index 430ef01d..4d1ee058 100644
--- a/test_data/golang/test_main/aas_core_meta.v3/expected_output/types/types.go
+++ b/test_data/golang/test_main/aas_core_meta.v3/expected_output/types/types.go
@@ -11504,13 +11504,11 @@ func (eds *EmbeddedDataSpecification) DescendOnce(
 		return
 	}
 
-	if eds.dataSpecification != nil {
-		abort = action(
-			eds.dataSpecification,
-		)
-		if abort {
-			return
-		}
+	abort = action(
+		eds.dataSpecification,
+	)
+	if abort {
+		return
 	}
 
 	return
@@ -11538,19 +11536,17 @@ func (eds *EmbeddedDataSpecification) Descend(
 		return
 	}
 
-	if eds.dataSpecification != nil {
-		abort = action(
-			eds.dataSpecification,
-		)
-		if abort {
-			return
-		}
-		abort = eds.dataSpecification.Descend(
-			action,
-		)
-		if abort {
-			return
-		}
+	abort = action(
+		eds.dataSpecification,
+	)
+	if abort {
+		return
+	}
+	abort = eds.dataSpecification.Descend(
+		action,
+	)
+	if abort {
+		return
 	}
 
 	return
@@ -11560,10 +11556,11 @@ func (eds *EmbeddedDataSpecification) Descend(
 // the given properties.
 func NewEmbeddedDataSpecification(
 	dataSpecificationContent IDataSpecificationContent,
+	dataSpecification IReference,
 ) *EmbeddedDataSpecification {
 	return &EmbeddedDataSpecification{
 		dataSpecificationContent: dataSpecificationContent,
-		dataSpecification: nil,
+		dataSpecification: dataSpecification,
 	}
 }
 
diff --git a/test_data/golang/test_main/aas_core_meta.v3/expected_output/verification/verification.go b/test_data/golang/test_main/aas_core_meta.v3/expected_output/verification/verification.go
index aa61899f..4bc3cc01 100644
--- a/test_data/golang/test_main/aas_core_meta.v3/expected_output/verification/verification.go
+++ b/test_data/golang/test_main/aas_core_meta.v3/expected_output/verification/verification.go
@@ -12351,7 +12351,16 @@ func VerifyEmbeddedDataSpecification(
 		}
 	}
 
-	if that.DataSpecification() != nil {
+	if that.DataSpecification() == nil {
+		abort = onError(
+			newVerificationError(
+				"Required property not set: DataSpecification",
+			),
+		)
+		if abort {
+			return
+		}
+	} else {
 		abort = Verify(
 			that.DataSpecification(),
 			func(err *VerificationError) bool {
@@ -12793,7 +12802,7 @@ func VerifyDataSpecificationIEC61360(
 		)) {
 		abort = onError(
 			newVerificationError(
-				"Constraint AASc-002: preferred name shall be provided at " +
+				"Constraint AASc-3a-002: preferred name shall be provided at " +
 				"least in English.",
 			),
 		)
@@ -13661,18 +13670,6 @@ func VerifyPathType(
 		}
 	}
 
-	if !MatchesRFC8089Path(that) {
-		abort = onError(
-			newVerificationError(
-				"The value must represent a valid file URI scheme according " +
-				"to RFC 8089.",
-			),
-		)
-		if abort {
-			return
-		}
-	}
-
 	return
 }
 
diff --git a/test_data/golang/test_main/aas_core_meta.v3/expected_output/xmlization/xmlization.go b/test_data/golang/test_main/aas_core_meta.v3/expected_output/xmlization/xmlization.go
index 81d21d48..85807647 100644
--- a/test_data/golang/test_main/aas_core_meta.v3/expected_output/xmlization/xmlization.go
+++ b/test_data/golang/test_main/aas_core_meta.v3/expected_output/xmlization/xmlization.go
@@ -9714,6 +9714,7 @@ func readEmbeddedDataSpecificationAsSequence(
 	var theDataSpecification aastypes.IReference
 
 	foundDataSpecificationContent := false
+	foundDataSpecification := false
 
 	for {
 		current, err = skipEmptyTextWhitespaceAndComments(decoder, current)
@@ -9772,6 +9773,7 @@ func readEmbeddedDataSpecificationAsSequence(
 				decoder,
 				current,
 			)
+			foundDataSpecification = true
 
 		default:
 			valueErr = newDeserializationError(
@@ -9824,10 +9826,15 @@ func readEmbeddedDataSpecificationAsSequence(
 		return
 	}
 
+	if !foundDataSpecification {
+		err = newDeserializationError(
+			"The required property 'dataSpecification' is missing",
+		)
+		return
+	}
+
 	instance = aastypes.NewEmbeddedDataSpecification(
 		theDataSpecificationContent,
-	)
-	instance.SetDataSpecification(
 		theDataSpecification,
 	)
 	return
@@ -21747,39 +21754,35 @@ func writeEmbeddedDataSpecificationAsSequence(
 
 	// region DataSpecification
 
-	theDataSpecification := that.DataSpecification()
-
-	if theDataSpecification != nil {
-		err = writeStartElement(
-			encoder,
-			"dataSpecification",
-			false,
-		)
-		if err != nil {
-			return
-		}
-		err = writeReferenceAsSequence(
-			encoder,
-			theDataSpecification,
-		)
-		if err != nil {
-			if seriaErr, ok := err.(*SerializationError); ok {
-				seriaErr.Path.PrependName(
-					&aasreporting.NameSegment{
-						Name: "DataSpecification()",
-					},
-				)
-			}
-			return
-		}
-		err = writeEndElement(
-			encoder,
-			"dataSpecification",
-			false,
-		)
-		if err != nil {
-			return
+	err = writeStartElement(
+		encoder,
+		"dataSpecification",
+		false,
+	)
+	if err != nil {
+		return
+	}
+	err = writeReferenceAsSequence(
+		encoder,
+		that.DataSpecification(),
+	)
+	if err != nil {
+		if seriaErr, ok := err.(*SerializationError); ok {
+			seriaErr.Path.PrependName(
+				&aasreporting.NameSegment{
+					Name: "DataSpecification()",
+				},
+			)
 		}
+		return
+	}
+	err = writeEndElement(
+		encoder,
+		"dataSpecification",
+		false,
+	)
+	if err != nil {
+		return
 	}
 
 	err = encoder.Flush()
diff --git a/test_data/intermediate/real_meta_models/aas_core_meta.v3/expected_symbol_table.txt b/test_data/intermediate/real_meta_models/aas_core_meta.v3/expected_symbol_table.txt
index 0c5e4b3d..84cf4f46 100644
--- a/test_data/intermediate/real_meta_models/aas_core_meta.v3/expected_symbol_table.txt
+++ b/test_data/intermediate/real_meta_models/aas_core_meta.v3/expected_symbol_table.txt
@@ -814,18 +814,6 @@ SymbolTable(
                 original_node=...),
               original_node=...)"""),
           specified_for='Reference to ConstrainedPrimitive Identifier',
-          parsed=...),
-        Invariant(
-          description='The value must represent a valid file URI scheme according to RFC 8089.',
-          body=textwrap.dedent("""\
-            FunctionCall(
-              name='matches_RFC_8089_path',
-              args=[
-                Name(
-                  identifier='self',
-                  original_node=...)],
-              original_node=...)"""),
-          specified_for='Reference to ConstrainedPrimitive Path_type',
           parsed=...)],
       invariant_id_set=...,
       description=DescriptionOfOurType(
@@ -25638,10 +25626,8 @@ SymbolTable(
           parsed=...),
         Property(
           name='data_specification',
-          type_annotation=OptionalTypeAnnotation(
-            value=OurTypeAnnotation(
-              our_type='Reference to our type Reference',
-              parsed=...),
+          type_annotation=OurTypeAnnotation(
+            our_type='Reference to our type Reference',
             parsed=...),
           description=DescriptionOfProperty(
             summary='<paragraph>Reference to the data specification</paragraph>',
@@ -25663,14 +25649,10 @@ SymbolTable(
             parsed=...),
           Argument(
             name='data_specification',
-            type_annotation=OptionalTypeAnnotation(
-              value=OurTypeAnnotation(
-                our_type='Reference to our type Reference',
-                parsed=...),
-              parsed=...),
-            default=DefaultPrimitive(
-              value=None,
+            type_annotation=OurTypeAnnotation(
+              our_type='Reference to our type Reference',
               parsed=...),
+            default=None,
             parsed=...)],
         returns=None,
         description=None,
@@ -27343,7 +27325,7 @@ SymbolTable(
           specified_for='Reference to ConcreteClass Data_specification_IEC_61360',
           parsed=...),
         Invariant(
-          description='Constraint AASc-002: preferred name shall be provided at least in English.',
+          description='Constraint AASc-3a-002: preferred name shall be provided at least in English.',
           body=textwrap.dedent("""\
             Any(
               generator=ForEach(
diff --git a/test_data/java/test_main/aas_core_meta.v3/expected_output/copying/Copying.java b/test_data/java/test_main/aas_core_meta.v3/expected_output/copying/Copying.java
index cf725946..b8759a93 100644
--- a/test_data/java/test_main/aas_core_meta.v3/expected_output/copying/Copying.java
+++ b/test_data/java/test_main/aas_core_meta.v3/expected_output/copying/Copying.java
@@ -507,7 +507,7 @@ public IClass transformEmbeddedDataSpecification(
         ) {
             return new EmbeddedDataSpecification(
                 that.getDataSpecificationContent(),
-                that.getDataSpecification().orElse(null));
+                that.getDataSpecification());
         }
 
         @Override
@@ -2513,7 +2513,7 @@ public IClass transformEmbeddedDataSpecification (
         ) {
             return new EmbeddedDataSpecification(
                 deep(that.getDataSpecificationContent()),
-                that.getDataSpecification().orElse(null)
+                deep(that.getDataSpecification())
             );
         }
 
diff --git a/test_data/java/test_main/aas_core_meta.v3/expected_output/enhancing/EnhancedEmbeddedDataSpecification.java b/test_data/java/test_main/aas_core_meta.v3/expected_output/enhancing/EnhancedEmbeddedDataSpecification.java
index 564dc612..89b792a5 100644
--- a/test_data/java/test_main/aas_core_meta.v3/expected_output/enhancing/EnhancedEmbeddedDataSpecification.java
+++ b/test_data/java/test_main/aas_core_meta.v3/expected_output/enhancing/EnhancedEmbeddedDataSpecification.java
@@ -40,7 +40,7 @@ public void setDataSpecificationContent(IDataSpecificationContent dataSpecificat
   }
 
   @Override
-  public Optional<IReference> getDataSpecification() {
+  public IReference getDataSpecification() {
     return instance.getDataSpecification();
   }
 
diff --git a/test_data/java/test_main/aas_core_meta.v3/expected_output/enhancing/Wrapper.java b/test_data/java/test_main/aas_core_meta.v3/expected_output/enhancing/Wrapper.java
index 986da172..d2ae1392 100644
--- a/test_data/java/test_main/aas_core_meta.v3/expected_output/enhancing/Wrapper.java
+++ b/test_data/java/test_main/aas_core_meta.v3/expected_output/enhancing/Wrapper.java
@@ -3116,18 +3116,16 @@ public IClass transformEmbeddedDataSpecification(
     IDataSpecificationContent castedDataSpecificationContent = (IDataSpecificationContent) transformedDataSpecificationContent;
     that.setDataSpecificationContent(castedDataSpecificationContent);
 
-    if (that.getDataSpecification().isPresent()) {
-      IReference dataSpecification = that.getDataSpecification().get();
-      IClass transformedDataSpecification = transform(dataSpecification);
-      if (!(transformedDataSpecification instanceof IReference)) {
-        throw new UnsupportedOperationException(
-          "Expected the transformed value to be a IReference " +
-          ", but got: " + transformedDataSpecification
-        );
-      }
-      IReference castedDataSpecification = (IReference) transformedDataSpecification;
-      that.setDataSpecification(castedDataSpecification);
+    IReference dataSpecification = that.getDataSpecification();
+    IClass transformedDataSpecification = transform(dataSpecification);
+    if (!(transformedDataSpecification instanceof IReference)) {
+      throw new UnsupportedOperationException(
+        "Expected the transformed value to be a IReference " +
+        ", but got: " + transformedDataSpecification
+      );
     }
+    IReference castedDataSpecification = (IReference) transformedDataSpecification;
+    that.setDataSpecification(castedDataSpecification);
 
     Optional<EnhancementT> enhancement = enhancementFactory.apply(that);
     return !enhancement.isPresent()
diff --git a/test_data/java/test_main/aas_core_meta.v3/expected_output/jsonization/Jsonization.java b/test_data/java/test_main/aas_core_meta.v3/expected_output/jsonization/Jsonization.java
index 06695fec..385b1110 100644
--- a/test_data/java/test_main/aas_core_meta.v3/expected_output/jsonization/Jsonization.java
+++ b/test_data/java/test_main/aas_core_meta.v3/expected_output/jsonization/Jsonization.java
@@ -10978,6 +10978,12 @@ private static Result<EmbeddedDataSpecification> tryEmbeddedDataSpecificationFro
           return Result.failure(error);
         }
 
+        if (theDataSpecification == null) {
+          final Reporting.Error error = new Reporting.Error(
+            "Required property \"dataSpecification\" is missing");
+          return Result.failure(error);
+        }
+
         return Result.success(new EmbeddedDataSpecification(
           theDataSpecificationContent,
           theDataSpecification));
@@ -15118,10 +15124,8 @@ public JsonNode transformEmbeddedDataSpecification(
         result.set("dataSpecificationContent", transform(
           that.getDataSpecificationContent()));
 
-        if (that.getDataSpecification().isPresent()) {
-          result.set("dataSpecification", transform(
-            that.getDataSpecification().get()));
-        }
+        result.set("dataSpecification", transform(
+          that.getDataSpecification()));
 
         return result;
       }
diff --git a/test_data/java/test_main/aas_core_meta.v3/expected_output/types/impl/EmbeddedDataSpecification.java b/test_data/java/test_main/aas_core_meta.v3/expected_output/types/impl/EmbeddedDataSpecification.java
index 0ab22470..1b1fbdc9 100644
--- a/test_data/java/test_main/aas_core_meta.v3/expected_output/types/impl/EmbeddedDataSpecification.java
+++ b/test_data/java/test_main/aas_core_meta.v3/expected_output/types/impl/EmbeddedDataSpecification.java
@@ -40,19 +40,15 @@ public class EmbeddedDataSpecification implements IEmbeddedDataSpecification {
    */
   private IReference dataSpecification;
 
-  public EmbeddedDataSpecification(IDataSpecificationContent dataSpecificationContent) {
-    this.dataSpecificationContent = Objects.requireNonNull(
-      dataSpecificationContent,
-      "Argument \"dataSpecificationContent\" must be non-null.");
-  }
-
   public EmbeddedDataSpecification(
     IDataSpecificationContent dataSpecificationContent,
     IReference dataSpecification) {
     this.dataSpecificationContent = Objects.requireNonNull(
       dataSpecificationContent,
       "Argument \"dataSpecificationContent\" must be non-null.");
-    this.dataSpecification = dataSpecification;
+    this.dataSpecification = Objects.requireNonNull(
+      dataSpecification,
+      "Argument \"dataSpecification\" must be non-null.");
   }
 
   @Override
@@ -68,13 +64,15 @@ public void setDataSpecificationContent(IDataSpecificationContent dataSpecificat
   }
 
   @Override
-  public Optional<IReference> getDataSpecification() {
-    return Optional.ofNullable(dataSpecification);
+  public IReference getDataSpecification() {
+    return dataSpecification;
   }
 
   @Override
   public void setDataSpecification(IReference dataSpecification) {
-    this.dataSpecification = dataSpecification;
+    this.dataSpecification = Objects.requireNonNull(
+      dataSpecification,
+      "Argument \"dataSpecification\" must be non-null.");
   }
 
   /**
diff --git a/test_data/java/test_main/aas_core_meta.v3/expected_output/types/model/IEmbeddedDataSpecification.java b/test_data/java/test_main/aas_core_meta.v3/expected_output/types/model/IEmbeddedDataSpecification.java
index 0de1d31e..a7df10ad 100644
--- a/test_data/java/test_main/aas_core_meta.v3/expected_output/types/model/IEmbeddedDataSpecification.java
+++ b/test_data/java/test_main/aas_core_meta.v3/expected_output/types/model/IEmbeddedDataSpecification.java
@@ -26,7 +26,7 @@ public interface IEmbeddedDataSpecification extends IClass {
   /**
    * Reference to the data specification
    */
-  Optional<IReference> getDataSpecification();
+  IReference getDataSpecification();
 
   void setDataSpecification(IReference dataSpecification);
 }
diff --git a/test_data/java/test_main/aas_core_meta.v3/expected_output/verification/Verification.java b/test_data/java/test_main/aas_core_meta.v3/expected_output/verification/Verification.java
index 0878dbad..71410ae3 100644
--- a/test_data/java/test_main/aas_core_meta.v3/expected_output/verification/Verification.java
+++ b/test_data/java/test_main/aas_core_meta.v3/expected_output/verification/Verification.java
@@ -8879,16 +8879,14 @@ public Stream<Reporting.Error> transformEmbeddedDataSpecification(
               return error;
             }));
 
-      if (that.getDataSpecification().isPresent()) {
-        errorStream = Stream.<Reporting.Error>concat(errorStream,
-          Stream.of(that.getDataSpecification().get())
-            .flatMap(Verification::verifyToErrorStream)
-              .map(error -> {
-                error.prependSegment(
-                  new Reporting.NameSegment("dataSpecification"));
-                return error;
-              }));
-      }
+      errorStream = Stream.<Reporting.Error>concat(errorStream,
+        Stream.of(that.getDataSpecification())
+          .flatMap(Verification::verifyToErrorStream)
+            .map(error -> {
+              error.prependSegment(
+                new Reporting.NameSegment("dataSpecification"));
+              return error;
+            }));
 
       return errorStream;
     }
@@ -9151,7 +9149,7 @@ public Stream<Reporting.Error> transformDataSpecificationIec61360(
         errorStream = Stream.<Reporting.Error>concat(errorStream,
           Stream.of(new Reporting.Error(
             "Invariant violated:\n" +
-            "Constraint AASc-002: preferred name shall be provided at " +
+            "Constraint AASc-3a-002: preferred name shall be provided at " +
             "least in English.")));
       }
 
@@ -9782,14 +9780,6 @@ public static Stream<Reporting.Error> verifyPathType (
           "Identifier shall have a maximum length of 2000 characters.")));
     }
 
-    if (!matchesRfc8089Path(that)) {
-      errorStream = Stream.<Reporting.Error>concat(errorStream,
-        Stream.of(new Reporting.Error(
-          "Invariant violated:\n" +
-          "The value must represent a valid file URI scheme according " +
-          "to RFC 8089.")));
-    }
-
     return errorStream;
   }
 
diff --git a/test_data/java/test_main/aas_core_meta.v3/expected_output/xmlization/Xmlization.java b/test_data/java/test_main/aas_core_meta.v3/expected_output/xmlization/Xmlization.java
index 5ca25813..36dd599e 100644
--- a/test_data/java/test_main/aas_core_meta.v3/expected_output/xmlization/Xmlization.java
+++ b/test_data/java/test_main/aas_core_meta.v3/expected_output/xmlization/Xmlization.java
@@ -13332,6 +13332,13 @@ private static Result<EmbeddedDataSpecification> tryEmbeddedDataSpecificationFro
         return Result.failure(error);
       }
 
+      if (theDataSpecification == null) {
+        final Reporting.Error error = new Reporting.Error(
+          "The required property dataSpecification has not been given " +
+          "in the XML representation of an instance of class EmbeddedDataSpecification");
+        return Result.failure(error);
+      }
+
       return Result.success(new EmbeddedDataSpecification(
         theDataSpecificationContent,
         theDataSpecification));
@@ -21725,20 +21732,18 @@ private void embeddedDataSpecificationToSequence(
       }
 
       try {
-        if (that.getDataSpecification().isPresent()) {
-          writer.writeStartElement(
-            "dataSpecification");
-          if (topLevel) {
-            writer.writeNamespace("xmlns", AAS_NAME_SPACE);
-            topLevel = false;
-          }
+        writer.writeStartElement(
+          "dataSpecification");
+        if (topLevel) {
+          writer.writeNamespace("xmlns", AAS_NAME_SPACE);
+          topLevel = false;
+        }
 
-          this.referenceToSequence(
-            that.getDataSpecification().get(),
-            writer);
+        this.referenceToSequence(
+          that.getDataSpecification(),
+          writer);
 
-          writer.writeEndElement();
-        }
+        writer.writeEndElement();
       } catch (XMLStreamException exception) {
         throw new SerializeException("",exception.getMessage());
       }
diff --git a/test_data/jsonschema/test_main/aas_core_meta.v3/expected_output/schema.json b/test_data/jsonschema/test_main/aas_core_meta.v3/expected_output/schema.json
index 81cd1848..a46c51d8 100644
--- a/test_data/jsonschema/test_main/aas_core_meta.v3/expected_output/schema.json
+++ b/test_data/jsonschema/test_main/aas_core_meta.v3/expected_output/schema.json
@@ -513,7 +513,8 @@
         }
       },
       "required": [
-        "dataSpecificationContent"
+        "dataSpecificationContent",
+        "dataSpecification"
       ]
     },
     "Entity": {
@@ -673,18 +674,9 @@
           "properties": {
             "value": {
               "type": "string",
-              "allOf": [
-                {
-                  "minLength": 1,
-                  "maxLength": 2000
-                },
-                {
-                  "pattern": "^([\\x09\\x0a\\x0d\\x20-\\ud7ff\\ue000-\\ufffd]|\\ud800[\\udc00-\\udfff]|[\\ud801-\\udbfe][\\udc00-\\udfff]|\\udbff[\\udc00-\\udfff])*$"
-                },
-                {
-                  "pattern": "^file:(//((localhost|(\\[((([0-9A-Fa-f]{1,4}:){6}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|::([0-9A-Fa-f]{1,4}:){5}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|([0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){4}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:)?[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){3}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){0,2}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){2}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){0,3}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}:([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){0,4}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){0,5}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}|(([0-9A-Fa-f]{1,4}:){0,6}[0-9A-Fa-f]{1,4})?::)|[vV][0-9A-Fa-f]+\\.([a-zA-Z0-9\\-._~]|[!$&'()*+,;=]|:)+)\\]|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])|([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=])*)))?/((([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))+(/(([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))*)*)?|/((([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))+(/(([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))*)*)?)$"
-                }
-              ]
+              "minLength": 1,
+              "maxLength": 2000,
+              "pattern": "^([\\x09\\x0a\\x0d\\x20-\\ud7ff\\ue000-\\ufffd]|\\ud800[\\udc00-\\udfff]|[\\ud801-\\udbfe][\\udc00-\\udfff]|\\udbff[\\udc00-\\udfff])*$"
             },
             "contentType": {
               "type": "string",
@@ -1280,18 +1272,9 @@
       "properties": {
         "path": {
           "type": "string",
-          "allOf": [
-            {
-              "minLength": 1,
-              "maxLength": 2000
-            },
-            {
-              "pattern": "^([\\x09\\x0a\\x0d\\x20-\\ud7ff\\ue000-\\ufffd]|\\ud800[\\udc00-\\udfff]|[\\ud801-\\udbfe][\\udc00-\\udfff]|\\udbff[\\udc00-\\udfff])*$"
-            },
-            {
-              "pattern": "^file:(//((localhost|(\\[((([0-9A-Fa-f]{1,4}:){6}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|::([0-9A-Fa-f]{1,4}:){5}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|([0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){4}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:)?[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){3}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){0,2}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){2}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){0,3}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}:([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){0,4}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){0,5}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}|(([0-9A-Fa-f]{1,4}:){0,6}[0-9A-Fa-f]{1,4})?::)|[vV][0-9A-Fa-f]+\\.([a-zA-Z0-9\\-._~]|[!$&'()*+,;=]|:)+)\\]|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])|([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=])*)))?/((([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))+(/(([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))*)*)?|/((([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))+(/(([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))*)*)?)$"
-            }
-          ]
+          "minLength": 1,
+          "maxLength": 2000,
+          "pattern": "^([\\x09\\x0a\\x0d\\x20-\\ud7ff\\ue000-\\ufffd]|\\ud800[\\udc00-\\udfff]|[\\ud801-\\udbfe][\\udc00-\\udfff]|\\udbff[\\udc00-\\udfff])*$"
         },
         "contentType": {
           "type": "string",
diff --git a/test_data/parse/real_meta_models/aas_core_meta.v3/expected_symbol_table.txt b/test_data/parse/real_meta_models/aas_core_meta.v3/expected_symbol_table.txt
index 87f5e977..37cc472c 100644
--- a/test_data/parse/real_meta_models/aas_core_meta.v3/expected_symbol_table.txt
+++ b/test_data/parse/real_meta_models/aas_core_meta.v3/expected_symbol_table.txt
@@ -443,18 +443,7 @@ UnverifiedSymbolTable(
         'Identifier'],
       properties=[],
       methods=[],
-      invariants=[
-        Invariant(
-          description='The value must represent a valid file URI scheme according to RFC 8089.',
-          body=textwrap.dedent("""\
-            FunctionCall(
-              name='matches_RFC_8089_path',
-              args=[
-                Name(
-                  identifier='self',
-                  original_node=...)],
-              original_node=...)"""),
-          node=...)],
+      invariants=[],
       serialization=None,
       description=Description(
         document=...,
@@ -10843,12 +10832,8 @@ UnverifiedSymbolTable(
           node=...),
         Property(
           name='data_specification',
-          type_annotation=SubscriptedTypeAnnotation(
-            identifier='Optional',
-            subscripts=[
-              AtomicTypeAnnotation(
-                identifier='Reference',
-                node=...)],
+          type_annotation=AtomicTypeAnnotation(
+            identifier='Reference',
             node=...),
           description=Description(
             document=...,
@@ -10873,15 +10858,10 @@ UnverifiedSymbolTable(
               node=...),
             Argument(
               name='data_specification',
-              type_annotation=SubscriptedTypeAnnotation(
-                identifier='Optional',
-                subscripts=[
-                  AtomicTypeAnnotation(
-                    identifier='Reference',
-                    node=...)],
-                node=...),
-              default=Default(
+              type_annotation=AtomicTypeAnnotation(
+                identifier='Reference',
                 node=...),
+              default=None,
               node=...)],
           returns=None,
           description=None,
@@ -12040,7 +12020,7 @@ UnverifiedSymbolTable(
               original_node=...)"""),
           node=...),
         Invariant(
-          description='Constraint AASc-002: preferred name shall be provided at least in English.',
+          description='Constraint AASc-3a-002: preferred name shall be provided at least in English.',
           body=textwrap.dedent("""\
             Any(
               generator=ForEach(
diff --git a/test_data/python/test_main/aas_core_meta.v3/expected_output/jsonization.py b/test_data/python/test_main/aas_core_meta.v3/expected_output/jsonization.py
index a704e24c..2238c0ec 100644
--- a/test_data/python/test_main/aas_core_meta.v3/expected_output/jsonization.py
+++ b/test_data/python/test_main/aas_core_meta.v3/expected_output/jsonization.py
@@ -9579,6 +9579,11 @@ def embedded_data_specification_from_jsonable(
             "The required property 'dataSpecificationContent' is missing"
         )
 
+    if setter.data_specification is None:
+        raise DeserializationException(
+            "The required property 'dataSpecification' is missing"
+        )
+
     return aas_types.EmbeddedDataSpecification(
         setter.data_specification_content,
         setter.data_specification
@@ -13173,10 +13178,9 @@ def transform_embedded_data_specification(
             self.transform(that.data_specification_content)
         )
 
-        if that.data_specification is not None:
-            jsonable['dataSpecification'] = (
-                self.transform(that.data_specification)
-            )
+        jsonable['dataSpecification'] = (
+            self.transform(that.data_specification)
+        )
 
         return jsonable
 
diff --git a/test_data/python/test_main/aas_core_meta.v3/expected_output/types.py b/test_data/python/test_main/aas_core_meta.v3/expected_output/types.py
index 442b46df..3cc9d320 100644
--- a/test_data/python/test_main/aas_core_meta.v3/expected_output/types.py
+++ b/test_data/python/test_main/aas_core_meta.v3/expected_output/types.py
@@ -5558,7 +5558,7 @@ class EmbeddedDataSpecification(Class):
     data_specification_content: 'DataSpecificationContent'
 
     #: Reference to the data specification
-    data_specification: Optional['Reference']
+    data_specification: 'Reference'
 
     def descend_once(self) -> Iterator[Class]:
         """
@@ -5570,8 +5570,7 @@ def descend_once(self) -> Iterator[Class]:
         """
         yield self.data_specification_content
 
-        if self.data_specification is not None:
-            yield self.data_specification
+        yield self.data_specification
 
     def descend(self) -> Iterator[Class]:
         """
@@ -5583,10 +5582,9 @@ def descend(self) -> Iterator[Class]:
 
         yield from self.data_specification_content.descend()
 
-        if self.data_specification is not None:
-            yield self.data_specification
+        yield self.data_specification
 
-            yield from self.data_specification.descend()
+        yield from self.data_specification.descend()
 
     def accept(self, visitor: "AbstractVisitor") -> None:
         """Dispatch the :paramref:`visitor` on this instance."""
@@ -5621,7 +5619,7 @@ def transform_with_context(
     def __init__(
             self,
             data_specification_content: 'DataSpecificationContent',
-            data_specification: Optional['Reference'] = None
+            data_specification: 'Reference'
     ) -> None:
         """Initialize with the given values."""
         self.data_specification_content = data_specification_content
diff --git a/test_data/python/test_main/aas_core_meta.v3/expected_output/verification.py b/test_data/python/test_main/aas_core_meta.v3/expected_output/verification.py
index d3953416..a4fc6280 100644
--- a/test_data/python/test_main/aas_core_meta.v3/expected_output/verification.py
+++ b/test_data/python/test_main/aas_core_meta.v3/expected_output/verification.py
@@ -7904,15 +7904,14 @@ def transform_embedded_data_specification(
             )
             yield error
 
-        if that.data_specification is not None:
-            for error in self.transform(that.data_specification):
-                error.path._prepend(
-                    PropertySegment(
-                        that,
-                        'data_specification'
-                    )
+        for error in self.transform(that.data_specification):
+            error.path._prepend(
+                PropertySegment(
+                    that,
+                    'data_specification'
                 )
-                yield error
+            )
+            yield error
 
     # noinspection PyMethodMayBeStatic
     def transform_level_type(
@@ -8148,7 +8147,7 @@ def transform_data_specification_iec_61360(
             )
         ):
             yield Error(
-                'Constraint AASc-002: preferred name shall be provided at ' +
+                'Constraint AASc-3a-002: preferred name shall be provided at ' +
                 'least in English.'
             )
 
@@ -8586,12 +8585,6 @@ def verify_path_type(
             'Identifier shall have a maximum length of 2000 characters.'
         )
 
-    if not matches_rfc_8089_path(that):
-        yield Error(
-            'The value must represent a valid file URI scheme according ' +
-            'to RFC 8089.'
-        )
-
 
 def verify_qualifier_type(
         that: str
diff --git a/test_data/python/test_main/aas_core_meta.v3/expected_output/xmlization.py b/test_data/python/test_main/aas_core_meta.v3/expected_output/xmlization.py
index 6599c161..d5f397e8 100644
--- a/test_data/python/test_main/aas_core_meta.v3/expected_output/xmlization.py
+++ b/test_data/python/test_main/aas_core_meta.v3/expected_output/xmlization.py
@@ -24181,6 +24181,11 @@ def _read_embedded_data_specification_as_sequence(
             "The required property 'dataSpecificationContent' is missing"
         )
 
+    if reader_and_setter.data_specification is None:
+        raise DeserializationException(
+            "The required property 'dataSpecification' is missing"
+        )
+
     return aas_types.EmbeddedDataSpecification(
         reader_and_setter.data_specification_content,
         reader_and_setter.data_specification
@@ -30472,12 +30477,11 @@ def _write_embedded_data_specification_as_sequence(
         self.visit(that.data_specification_content)
         self._write_end_element('dataSpecificationContent')
 
-        if that.data_specification is not None:
-            self._write_start_element('dataSpecification')
-            self._write_reference_as_sequence(
-                that.data_specification
-            )
-            self._write_end_element('dataSpecification')
+        self._write_start_element('dataSpecification')
+        self._write_reference_as_sequence(
+            that.data_specification
+        )
+        self._write_end_element('dataSpecification')
 
     def visit_embedded_data_specification(
         self,
diff --git a/test_data/rdf_shacl/test_main/expected/aas_core_meta.v3/expected_output/shacl-schema.ttl b/test_data/rdf_shacl/test_main/expected/aas_core_meta.v3/expected_output/shacl-schema.ttl
index 192eee03..4b734c5c 100644
--- a/test_data/rdf_shacl/test_main/expected/aas_core_meta.v3/expected_output/shacl-schema.ttl
+++ b/test_data/rdf_shacl/test_main/expected/aas_core_meta.v3/expected_output/shacl-schema.ttl
@@ -424,7 +424,7 @@ aas:EmbeddedDataSpecificationShape a sh:NodeShape ;
         a sh:PropertyShape ;
         sh:path <https://admin-shell.io/aas/3/0/EmbeddedDataSpecification/dataSpecification> ;
         sh:class aas:Reference ;
-        sh:minCount 0 ;
+        sh:minCount 1 ;
         sh:maxCount 1 ;
     ] ;
 .
@@ -613,7 +613,6 @@ aas:FileShape a sh:NodeShape ;
         sh:minLength 1 ;
         sh:maxLength 2000 ;
         sh:pattern "^[\\x09\\x0A\\x0D\\x20-\\uD7FF\\uE000-\\uFFFD\\U00010000-\\U0010FFFF]*$" ;
-        sh:pattern "^file:(//((localhost|(\\[((([0-9A-Fa-f]{1,4}:){6}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|::([0-9A-Fa-f]{1,4}:){5}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|([0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){4}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:)?[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){3}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){,2}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){2}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){,3}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}:([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){,4}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){,5}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}|(([0-9A-Fa-f]{1,4}:){,6}[0-9A-Fa-f]{1,4})?::)|[vV][0-9A-Fa-f]+\\.([a-zA-Z0-9\\-._~]|[!$&'()*+,;=]|:)+)\\]|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])|([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=])*)))?/((([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))+(/(([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))*)*)?|/((([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))+(/(([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))*)*)?)$" ;
     ] ;
     sh:property [
         a sh:PropertyShape ;
@@ -1161,7 +1160,6 @@ aas:ResourceShape a sh:NodeShape ;
         sh:minLength 1 ;
         sh:maxLength 2000 ;
         sh:pattern "^[\\x09\\x0A\\x0D\\x20-\\uD7FF\\uE000-\\uFFFD\\U00010000-\\U0010FFFF]*$" ;
-        sh:pattern "^file:(//((localhost|(\\[((([0-9A-Fa-f]{1,4}:){6}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|::([0-9A-Fa-f]{1,4}:){5}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|([0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){4}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:)?[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){3}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){,2}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){2}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){,3}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}:([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){,4}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))|(([0-9A-Fa-f]{1,4}:){,5}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}|(([0-9A-Fa-f]{1,4}:){,6}[0-9A-Fa-f]{1,4})?::)|[vV][0-9A-Fa-f]+\\.([a-zA-Z0-9\\-._~]|[!$&'()*+,;=]|:)+)\\]|([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])|([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=])*)))?/((([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))+(/(([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))*)*)?|/((([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))+(/(([a-zA-Z0-9\\-._~]|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'()*+,;=]|[:@]))*)*)?)$" ;
     ] ;
     sh:property [
         a sh:PropertyShape ;
diff --git a/test_data/typescript/test_main/aas_core_meta.v3/expected_output/jsonization.ts b/test_data/typescript/test_main/aas_core_meta.v3/expected_output/jsonization.ts
index 3a466e03..0d166f6f 100644
--- a/test_data/typescript/test_main/aas_core_meta.v3/expected_output/jsonization.ts
+++ b/test_data/typescript/test_main/aas_core_meta.v3/expected_output/jsonization.ts
@@ -14565,6 +14565,14 @@ export function embeddedDataSpecificationFromJsonable(
     );
   }
 
+  if (setter.dataSpecification === null) {
+    return newDeserializationError<
+      AasTypes.EmbeddedDataSpecification
+    >(
+      "The required property 'dataSpecification' is missing"
+    );
+  }
+
   return new AasCommon.Either<
     AasTypes.EmbeddedDataSpecification,
     DeserializationError
@@ -20525,10 +20533,8 @@ class Serializer extends AasTypes.AbstractTransformer<JsonObject> {
     jsonable["dataSpecificationContent"] =
       this.transform(that.dataSpecificationContent);
 
-    if (that.dataSpecification !== null) {
-      jsonable["dataSpecification"] =
-        this.transform(that.dataSpecification);
-    }
+    jsonable["dataSpecification"] =
+      this.transform(that.dataSpecification);
 
     return jsonable;
   }
diff --git a/test_data/typescript/test_main/aas_core_meta.v3/expected_output/types.ts b/test_data/typescript/test_main/aas_core_meta.v3/expected_output/types.ts
index 349c6461..ecb6838d 100644
--- a/test_data/typescript/test_main/aas_core_meta.v3/expected_output/types.ts
+++ b/test_data/typescript/test_main/aas_core_meta.v3/expected_output/types.ts
@@ -9941,7 +9941,7 @@ export class EmbeddedDataSpecification extends Class {
   /**
    * Reference to the data specification
    */
-  dataSpecification: Reference | null;
+  dataSpecification: Reference;
 
   /**
    * Iterate over the instances referenced from this instance.
@@ -9953,9 +9953,7 @@ export class EmbeddedDataSpecification extends Class {
   *descendOnce(): IterableIterator<Class> {
     yield this.dataSpecificationContent;
 
-    if (this.dataSpecification !== null) {
-      yield this.dataSpecification;
-    }
+    yield this.dataSpecification;
   }
 
   /**
@@ -9968,11 +9966,9 @@ export class EmbeddedDataSpecification extends Class {
 
     yield * this.dataSpecificationContent.descend();
 
-    if (this.dataSpecification !== null) {
-      yield this.dataSpecification;
+    yield this.dataSpecification;
 
-      yield * this.dataSpecification.descend();
-    }
+    yield * this.dataSpecification.descend();
   }
 
   /**
@@ -10029,7 +10025,7 @@ export class EmbeddedDataSpecification extends Class {
 
   constructor(
     dataSpecificationContent: IDataSpecificationContent,
-    dataSpecification: Reference | null = null
+    dataSpecification: Reference
   ) {
     super();
     this.dataSpecificationContent = dataSpecificationContent;
diff --git a/test_data/typescript/test_main/aas_core_meta.v3/expected_output/verification.ts b/test_data/typescript/test_main/aas_core_meta.v3/expected_output/verification.ts
index a40c748f..b0d961e2 100644
--- a/test_data/typescript/test_main/aas_core_meta.v3/expected_output/verification.ts
+++ b/test_data/typescript/test_main/aas_core_meta.v3/expected_output/verification.ts
@@ -9291,18 +9291,16 @@ class Verifier
         yield error;
       }
 
-      if (that.dataSpecification !== null) {
-        for (const error of this.transformWithContext(
-            that.dataSpecification, context)
-        ) {
-          error.path.prepend(
-            new PropertySegment(
-              that,
-              "dataSpecification"
-            )
-          );
-          yield error;
-        }
+      for (const error of this.transformWithContext(
+          that.dataSpecification, context)
+      ) {
+        error.path.prepend(
+          new PropertySegment(
+            that,
+            "dataSpecification"
+          )
+        );
+        yield error;
       }
     }
   }
@@ -9567,7 +9565,7 @@ class Verifier
       )
     )) {
       yield new VerificationError(
-        "Constraint AASc-002: preferred name shall be provided at " +
+        "Constraint AASc-3a-002: preferred name shall be provided at " +
         "least in English."
       )
     }
@@ -10143,13 +10141,6 @@ export function *verifyPathType(
       "Identifier shall have a maximum length of 2000 characters."
     )
   }
-
-  if (!matchesRfc8089Path(that)) {
-    yield new VerificationError(
-      "The value must represent a valid file URI scheme according " +
-      "to RFC 8089."
-    )
-  }
 }
 
 /**
diff --git a/test_data/xsd/test_main/aas_core_meta.v3/expected_output/schema.xsd b/test_data/xsd/test_main/aas_core_meta.v3/expected_output/schema.xsd
index 5a246096..e53ba2f9 100644
--- a/test_data/xsd/test_main/aas_core_meta.v3/expected_output/schema.xsd
+++ b/test_data/xsd/test_main/aas_core_meta.v3/expected_output/schema.xsd
@@ -284,7 +284,7 @@
           </xs:sequence>
         </xs:complexType>
       </xs:element>
-      <xs:element name="dataSpecification" type="reference_t" minOccurs="0" maxOccurs="1"/>
+      <xs:element name="dataSpecification" type="reference_t"/>
     </xs:sequence>
   </xs:group>
   <xs:group name="entity">
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