Move Clock dependency info to attribute

fixes modelica#1370

docs/2_2_common_mechanisms.adoc

@@ -804,7 +804,7 @@ In some clock semantics (e.g. <<MLS12>>), a clocked variable has a value only wh
 However, <<get-and-set-variable-values,`fmi3Get{VariableType}`>> will return the value computed at the last Clock activation time.
 Before the first Clock tick, clocked variables have their initial value.
 
-The association between <<clocked-variable,clocked variables>> and their <<Clock,Clocks>> is defined by the <<model-dependencies,model dependency>> elements <<ClockElement>>.
+The association between <<clocked-variable,clocked variables>> and their <<Clock,Clocks>> is defined by the attribute <<clocks>>.
 <<clocked-variable,Clocked variables>> can depend on multiple Clocks.
 _[For example, a global counter could be incremented by multiple tasks, each controlled by a different Clock.]_
 

docs/2_4_common_schema.adoc

@@ -1077,12 +1077,19 @@ The default value of this attribute is `false`.
 |
 [[previous,`previous`]]
 If present, this variable is a <<ClockedState>> and this attribute is a value reference to the variable with the previous value.
-Only clocked variables (they are listed in at least one of the <<clockedVariables>> lists) may have the <<previous>> attribute.
+Only clocked variables (i.e. variables with the attribute <<clocks>>) may have the <<previous>> attribute.
 Only variables with <<variability,`variability == discrete`>> may have a previous value.
 
 _[For example, if `previous == 3` for variable `8`, then variable `3` is the previous value of variable `8`. See also <<fmi3UpdateDiscreteStates>>._
 _Note: This is reverse compared to the <<derivative>> attribute.]_
 
+|`clocks`
+|
+[[clocks,`clocks`]]
+If present, this variable is clocked.
+The value of <<clocks>> is a list of value references of <<Clock>> variables this variable depends on.
+Only discrete variables can have this attribute.
+_[More rigorous importers requiring a variable to be dependent on a single clock can reject FMUs violating this restriction.]_
 |====
 
 If <<initial>> is not present, its value is defined by <<table-definition-initial>> based on the values of <<causality>> and <<variability>> (default [.underline]#underlined#):
@@ -1690,8 +1697,8 @@ latexmath:[{\dot{\mathbf{x}_c} := \mathbf{f}_{\mathit{der}}(\mathbf{x}_c, \mathb
 |`ClockedState`
 |
 [[ClockedState,`<ClockedState>`]]
-A <<ClockedState>> is part of the discrete state of a model partition and represented by a <<ClockElement,clocked>> variable.
-To which clock or clocks it belongs is described in <<ClockElement>>.
+A <<ClockedState>> is part of the discrete state of a model partition and represented by a clocked variable.
+To which Clock or Clocks it belongs is described by the attribute <<clocks>>.
 Each <<ClockedState>> must have the attribute <<previous>> to represent the previous value of this <<ClockedState>>.
 All <<ClockedState,clocked states>> must have <<variability,`variability == discrete`>>.
 
@@ -1735,20 +1742,11 @@ _The ordering of the variables in this list is defined by the exporting tool.]_
 
 For Co-Simulation, elements <<EventIndicator>> are ignored.
 _[If an FMU supports both Model Exchange and Co-Simulation, then the <<EventIndicator>> elements might be present, since it is needed for Model Exchange.]_
-
-|`Clock`
-|
-[[ClockElement,`<Clock>`]]
-List of all clocks and their clocked variables.
-All variables referenced by these lists must have <<variability,`variability == discrete`>>.
-A clocked variable my depend on multiple clocks and may therefore be listed in multiple <<ClockElement>> elements.
-_[More rigorous importers requiring a variable to be dependent on a single clock can reject FMUs violating this restriction.]_
-
 |====
 
-Elements <<Output>>, <<ContinuousStateDerivative>>, <<ClockedState>>, <<InitialUnknown>>, <<EventIndicator>> and <<ClockElement>> have (partially) the following attributes:
+Elements <<Output>>, <<ContinuousStateDerivative>>, <<ClockedState>>, <<InitialUnknown>>, and <<EventIndicator>> have (partially) the following attributes:
 
-.<<Output>>, <<ContinuousStateDerivative>>, <<ClockedState>>, <<InitialUnknown>>, <<EventIndicator>> and <<ClockElement>> attribute details.
+.<<Output>>, <<ContinuousStateDerivative>>, <<ClockedState>>, <<InitialUnknown>>, and <<EventIndicator>> attribute details.
 [[table-output-der-initialUknown-details]]
 [cols="1,5", options="header"]
 |====
@@ -1809,12 +1807,6 @@ Only for floating point type unknowns latexmath:[{\mathbf{v}_{\mathit{unknown}}}
 `=` <<tunable>>: tunable factor, latexmath:[{p \cdot \mathbf{v}_{\mathit{known},i}}] where latexmath:[{p}] is an expression that is evaluated before <<fmi3ExitInitializationMode>> is called and in <<EventMode>> due to event handling (ME) or at a communication point (CS and SE)
 
 `=` <<discrete>>: discrete factor, latexmath:[{d \cdot \mathbf{v}_{\mathit{known},i}}] where latexmath:[{d}] is an expression that is evaluated before <<fmi3ExitInitializationMode>> is called and in <<EventMode>> due to an external or internal event or at a communication point (CS and SE).
-
-|`clockedVariables`
-|
-[[clockedVariables, `clockedVariables`]]
-This element is only available with the <<ClockElement>> element and is a list of value references indicating clocked variables depending on this clock.
-
 |====
 
 _[Example 1:_

schema/fmi3ModelDescription.xsd

@@ -104,19 +104,6 @@ ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 									<xs:attribute name="valueReference" type="xs:unsignedInt" use="required"/>
 								</xs:complexType>
 							</xs:element>
-							<xs:element name="Clock" minOccurs="0" maxOccurs="unbounded">
-								<xs:complexType>
-									<xs:sequence>
-										<xs:element ref="Annotations" minOccurs="0"/>
-									</xs:sequence>
-									<xs:attribute name="valueReference" type="xs:unsignedInt" use="required"/>
-									<xs:attribute name="clockedVariables">
-										<xs:simpleType>
-											<xs:list itemType="xs:unsignedInt"/>
-										</xs:simpleType>
-									</xs:attribute>
-								</xs:complexType>
-							</xs:element>
 						</xs:sequence>
 					</xs:complexType>
 				</xs:element>

schema/fmi3Variable.xsd

@@ -350,6 +350,11 @@ ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 		<xs:attribute name="canHandleMultipleSetPerTimeInstant" type="xs:boolean"/>
 		<xs:attribute name="intermediateUpdate" type="xs:boolean"/>
 		<xs:attribute name="previous" type="xs:unsignedInt"/>
+		<xs:attribute name="clocks">
+			<xs:simpleType>
+				<xs:list itemType="xs:unsignedInt"/>
+			</xs:simpleType>
+		</xs:attribute>
 	</xs:complexType>
 
 	<xs:group name="fmi3Variable">