diff --git a/formats/repeat_repeat-expr_only.ksy b/formats/repeat_repeat-expr_only.ksy
new file mode 100644
index 000000000..c4d3183b1
--- /dev/null
+++ b/formats/repeat_repeat-expr_only.ksy
@@ -0,0 +1,6 @@
+meta:
+  id: repeat_expr_only
+seq:
+  - id: foo
+    type: u1
+    repeat-expr: 42
\ No newline at end of file
diff --git a/formats/repeat_repeat-until_only.ksy b/formats/repeat_repeat-until_only.ksy
new file mode 100644
index 000000000..265a1a0f2
--- /dev/null
+++ b/formats/repeat_repeat-until_only.ksy
@@ -0,0 +1,6 @@
+meta:
+  id: repeat_until_only
+seq:
+  - id: foo
+    type: u1
+    repeat-until: _ != 0
\ No newline at end of file
diff --git a/formats_err/repeat_bad_repeat-expr-and-until.ksy b/formats_err/repeat_bad_repeat-expr-and-until.ksy
new file mode 100644
index 000000000..7d14a65ac
--- /dev/null
+++ b/formats_err/repeat_bad_repeat-expr-and-until.ksy
@@ -0,0 +1,9 @@
+# repeat_bad_repeat-expr-and-until.ksy: /seq/0/repeat: error: expected eos / expr / until, got 'bad'
+meta:
+  id: repeat_bad_repeat_expr_and_until
+seq:
+  - id: foo
+    type: u1
+    repeat: bad
+    repeat-expr: 42
+    repeat-until: 'true'
diff --git a/formats_err/repeat_bad_repeat-expr.ksy b/formats_err/repeat_bad_repeat-expr.ksy
new file mode 100644
index 000000000..d419b3079
--- /dev/null
+++ b/formats_err/repeat_bad_repeat-expr.ksy
@@ -0,0 +1,8 @@
+# repeat_bad_repeat-expr.ksy: /seq/0/repeat: error: expected eos / expr / until, got 'bad'
+meta:
+  id: repeat_bad_repeat_expr
+seq:
+  - id: foo
+    type: u1
+    repeat: bad
+    repeat-expr: 42
diff --git a/formats_err/repeat_bad_repeat-until.ksy b/formats_err/repeat_bad_repeat-until.ksy
new file mode 100644
index 000000000..625d347e7
--- /dev/null
+++ b/formats_err/repeat_bad_repeat-until.ksy
@@ -0,0 +1,8 @@
+# repeat_bad_repeat-until.ksy: /seq/0/repeat: error: expected eos / expr / until, got 'bad'
+meta:
+  id: repeat_bad_repeat_until
+seq:
+  - id: foo
+    type: u1
+    repeat: bad
+    repeat-until: 'true'
diff --git a/formats_err/repeat_eos_repeat-expr-and-until.ksy b/formats_err/repeat_eos_repeat-expr-and-until.ksy
new file mode 100644
index 000000000..21e95a046
--- /dev/null
+++ b/formats_err/repeat_eos_repeat-expr-and-until.ksy
@@ -0,0 +1,9 @@
+# repeat_eos_repeat-expr-and-until.ksy: /seq/0/repeat: error: either `repeat: eos`, or `repeat-expr`, or `repeat-until` must be specified
+meta:
+  id: repeat_eos_repeat_expr_and_until
+seq:
+  - id: foo
+    type: u1
+    repeat: eos
+    repeat-expr: 42
+    repeat-until: 'true'
diff --git a/formats_err/repeat_eos_repeat-expr.ksy b/formats_err/repeat_eos_repeat-expr.ksy
new file mode 100644
index 000000000..e640bc26e
--- /dev/null
+++ b/formats_err/repeat_eos_repeat-expr.ksy
@@ -0,0 +1,8 @@
+# repeat_eos_repeat-expr.ksy: /seq/0/repeat: error: `repeat-expr` requires either a `repeat: expr` or absence of a `repeat` key
+meta:
+  id: repeat_eos_repeat_expr
+seq:
+  - id: foo
+    type: u1
+    repeat: eos
+    repeat-expr: 42
\ No newline at end of file
diff --git a/formats_err/repeat_eos_repeat-until.ksy b/formats_err/repeat_eos_repeat-until.ksy
new file mode 100644
index 000000000..f5345a2bd
--- /dev/null
+++ b/formats_err/repeat_eos_repeat-until.ksy
@@ -0,0 +1,8 @@
+# repeat_eos_repeat-until.ksy: /seq/0/repeat: error: `repeat-until` requires either a `repeat: until` or absence of a `repeat` key
+meta:
+  id: repeat_eos_repeat_until
+seq:
+  - id: foo
+    type: u1
+    repeat: eos
+    repeat-until: 'true'
diff --git a/formats_err/repeat_expr.ksy b/formats_err/repeat_expr.ksy
new file mode 100644
index 000000000..f1f33a3d6
--- /dev/null
+++ b/formats_err/repeat_expr.ksy
@@ -0,0 +1,7 @@
+# repeat_expr.ksy: /seq/0/repeat: error: `repeat: expr` requires a `repeat-expr` key
+meta:
+  id: repeat_expr
+seq:
+  - id: foo
+    type: u1
+    repeat: expr
diff --git a/formats_err/repeat_expr_repeat-expr-and-until.ksy b/formats_err/repeat_expr_repeat-expr-and-until.ksy
new file mode 100644
index 000000000..2304bb321
--- /dev/null
+++ b/formats_err/repeat_expr_repeat-expr-and-until.ksy
@@ -0,0 +1,9 @@
+# repeat_expr_repeat-expr-and-until.ksy: /seq/0/repeat: error: either `repeat: eos`, or `repeat-expr`, or `repeat-until` must be specified
+meta:
+  id: repeat_expr_repeat_expr_and_until
+seq:
+  - id: foo
+    type: u1
+    repeat: expr
+    repeat-expr: 42
+    repeat-until: 'true'
diff --git a/formats_err/repeat_expr_repeat-until.ksy b/formats_err/repeat_expr_repeat-until.ksy
new file mode 100644
index 000000000..362ae9504
--- /dev/null
+++ b/formats_err/repeat_expr_repeat-until.ksy
@@ -0,0 +1,8 @@
+# repeat_expr_repeat-until.ksy: /seq/0/repeat: error: `repeat-until` requires either a `repeat: until` or absence of a `repeat` key
+meta:
+  id: repeat_expr_repeat_until
+seq:
+  - id: foo
+    type: u1
+    repeat: expr
+    repeat-until: 'true'
diff --git a/formats_err/repeat_incompatible1.ksy b/formats_err/repeat_incompatible1.ksy
deleted file mode 100644
index f9cffa14d..000000000
--- a/formats_err/repeat_incompatible1.ksy
+++ /dev/null
@@ -1,8 +0,0 @@
-# repeat_incompatible1.ksy: /seq/0/repeat-until: error: unknown key found, expected: consume, doc, doc-ref, eos-error, id, if, include, repeat, terminator, type, valid
-meta:
-  id: repeat_incompatible1
-seq:
-  - id: foo
-    type: u1
-    repeat: eos
-    repeat-until: 'true'
diff --git a/formats_err/repeat_incompatible2.ksy b/formats_err/repeat_incompatible2.ksy
deleted file mode 100644
index f76383632..000000000
--- a/formats_err/repeat_incompatible2.ksy
+++ /dev/null
@@ -1,8 +0,0 @@
-# repeat_incompatible2.ksy: /seq/0/repeat: error: `repeat: expr` requires a `repeat-expr` expression
-meta:
-  id: repeat_incompatible2
-seq:
-  - id: foo
-    type: u1
-    repeat: expr
-    repeat-until: 'true'
diff --git a/formats_err/repeat_incompatible3.ksy b/formats_err/repeat_incompatible3.ksy
deleted file mode 100644
index 604b236ea..000000000
--- a/formats_err/repeat_incompatible3.ksy
+++ /dev/null
@@ -1,9 +0,0 @@
-# repeat_incompatible3.ksy: /seq/0/repeat-expr: error: unknown key found, expected: consume, doc, doc-ref, eos-error, id, if, include, repeat, repeat-until, terminator, type, valid
-meta:
-  id: repeat_incompatible3
-seq:
-  - id: foo
-    type: u1
-    repeat: until
-    repeat-until: 1 == 1
-    repeat-expr: 42
diff --git a/formats_err/repeat_until.ksy b/formats_err/repeat_until.ksy
new file mode 100644
index 000000000..7044e491c
--- /dev/null
+++ b/formats_err/repeat_until.ksy
@@ -0,0 +1,7 @@
+# repeat_until.ksy: /seq/0/repeat: error: `repeat: until` requires a `repeat-until` key
+meta:
+  id: repeat_until
+seq:
+  - id: foo
+    type: u1
+    repeat: until
diff --git a/formats_err/repeat_until_repeat-expr-and-until.ksy b/formats_err/repeat_until_repeat-expr-and-until.ksy
new file mode 100644
index 000000000..360fdad18
--- /dev/null
+++ b/formats_err/repeat_until_repeat-expr-and-until.ksy
@@ -0,0 +1,9 @@
+# repeat_until_repeat-expr-and-until.ksy: /seq/0/repeat: error: either `repeat: eos`, or `repeat-expr`, or `repeat-until` must be specified
+meta:
+  id: repeat_until_repeat_expr_and_until
+seq:
+  - id: foo
+    type: u1
+    repeat: until
+    repeat-expr: 42
+    repeat-until: 'true'
diff --git a/formats_err/repeat_until_repeat-expr.ksy b/formats_err/repeat_until_repeat-expr.ksy
new file mode 100644
index 000000000..b6b2078ce
--- /dev/null
+++ b/formats_err/repeat_until_repeat-expr.ksy
@@ -0,0 +1,8 @@
+# repeat_until_repeat-expr.ksy: /seq/0/repeat: error: `repeat-expr` requires either a `repeat: expr` or absence of a `repeat` key
+meta:
+  id: repeat_until_repeat_expr
+seq:
+  - id: foo
+    type: u1
+    repeat: until
+    repeat-expr: 42
diff --git a/formats_err/repeat_wo_expr.ksy b/formats_err/repeat_wo_expr.ksy
deleted file mode 100644
index 17f6a02f6..000000000
--- a/formats_err/repeat_wo_expr.ksy
+++ /dev/null
@@ -1,7 +0,0 @@
-# repeat_wo_expr.ksy: /seq/0/repeat: error: `repeat: expr` requires a `repeat-expr` expression
-meta:
-  id: repeat_wo_expr
-seq:
-  - id: foo
-    type: u1
-    repeat: expr
diff --git a/formats_err/repeat_wo_repeat.ksy b/formats_err/repeat_wo_repeat.ksy
deleted file mode 100644
index 4176bf146..000000000
--- a/formats_err/repeat_wo_repeat.ksy
+++ /dev/null
@@ -1,7 +0,0 @@
-# repeat_wo_repeat.ksy: /seq/0/repeat-until: error: unknown key found, expected: consume, doc, doc-ref, eos-error, id, if, include, repeat, terminator, type, valid
-meta:
-  id: repeat_wo_repeat
-seq:
-  - id: foo
-    type: u1
-    repeat-until: 'true'
diff --git a/formats_err/repeat_wo_until.ksy b/formats_err/repeat_wo_until.ksy
deleted file mode 100644
index 0aa03ab65..000000000
--- a/formats_err/repeat_wo_until.ksy
+++ /dev/null
@@ -1,7 +0,0 @@
-# repeat_wo_until.ksy: /seq/0/repeat: error: `repeat: until` requires a `repeat-until` expression
-meta:
-  id: repeat_wo_until
-seq:
-  - id: foo
-    type: u1
-    repeat: until