diff --git a/src/ifcopenshell-python/test/fixtures/rules/fail-lining-properties-1.0-None.ifc b/src/ifcopenshell-python/test/fixtures/rules/fail-lining-properties-1.0-None.ifc
new file mode 100644
index 0000000000..40441a1413
--- /dev/null
+++ b/src/ifcopenshell-python/test/fixtures/rules/fail-lining-properties-1.0-None.ifc
@@ -0,0 +1,11 @@
+ISO-10303-21;
+HEADER;
+FILE_DESCRIPTION(('ViewDefinition [CoordinationView]'),'2;1');
+FILE_NAME('','2023-02-03T21:03:39',(),(),'IfcOpenShell v0.7.0-07ee62eb9','IfcOpenShell v0.7.0-07ee62eb9','');
+FILE_SCHEMA(('IFC4'));
+ENDSEC;
+DATA;
+#1=IFCWINDOWLININGPROPERTIES('2W70Kvm_v3u9yS3fEKz8PE',$,$,$,1.,$,$,$,$,$,$,$,$,$,$,$);
+#2=IFCWINDOWTYPE('2sFDIHjAr5kQR0lJbTEoNk',$,'WindowType',$,$,(#1),$,$,$,$,$,$,$);
+ENDSEC;
+END-ISO-10303-21;
diff --git a/src/ifcopenshell-python/test/fixtures/rules/generate_21.py b/src/ifcopenshell-python/test/fixtures/rules/generate_21.py
new file mode 100644
index 0000000000..d402f26520
--- /dev/null
+++ b/src/ifcopenshell-python/test/fixtures/rules/generate_21.py
@@ -0,0 +1,13 @@
+import itertools
+import ifcopenshell
+
+def EXISTS(v): return v is not None
+def NOT(v): return not v
+
+for LiningDepth, LiningThickness in itertools.product((None, 1.), (None, 1.)):
+    f = ifcopenshell.file(schema="IFC4")
+    valid = NOT(EXISTS(LiningDepth) and NOT(EXISTS(LiningThickness)))
+    f.createIfcWindowType(ifcopenshell.guid.new(), None, 'WindowType', HasPropertySets=[
+        f.createIfcWindowLiningProperties(ifcopenshell.guid.new(), LiningDepth=LiningDepth, LiningThickness=LiningThickness)
+    ])
+    f.write(f"{'pass' if valid else 'fail'}-lining-properties-{LiningDepth}-{LiningThickness}.ifc")
\ No newline at end of file
diff --git a/src/ifcopenshell-python/test/fixtures/rules/pass-lining-properties-1.0-1.0.ifc b/src/ifcopenshell-python/test/fixtures/rules/pass-lining-properties-1.0-1.0.ifc
new file mode 100644
index 0000000000..c3b92c2dc1
--- /dev/null
+++ b/src/ifcopenshell-python/test/fixtures/rules/pass-lining-properties-1.0-1.0.ifc
@@ -0,0 +1,11 @@
+ISO-10303-21;
+HEADER;
+FILE_DESCRIPTION(('ViewDefinition [CoordinationView]'),'2;1');
+FILE_NAME('','2023-02-03T21:03:39',(),(),'IfcOpenShell v0.7.0-07ee62eb9','IfcOpenShell v0.7.0-07ee62eb9','');
+FILE_SCHEMA(('IFC4'));
+ENDSEC;
+DATA;
+#1=IFCWINDOWLININGPROPERTIES('3NGl9gqpf5pAlbFx$B7S05',$,$,$,1.,1.,$,$,$,$,$,$,$,$,$,$);
+#2=IFCWINDOWTYPE('3MDd04avLCdh6Ivz$WzUaX',$,'WindowType',$,$,(#1),$,$,$,$,$,$,$);
+ENDSEC;
+END-ISO-10303-21;
diff --git a/src/ifcopenshell-python/test/fixtures/rules/pass-lining-properties-None-1.0.ifc b/src/ifcopenshell-python/test/fixtures/rules/pass-lining-properties-None-1.0.ifc
new file mode 100644
index 0000000000..76343f973a
--- /dev/null
+++ b/src/ifcopenshell-python/test/fixtures/rules/pass-lining-properties-None-1.0.ifc
@@ -0,0 +1,11 @@
+ISO-10303-21;
+HEADER;
+FILE_DESCRIPTION(('ViewDefinition [CoordinationView]'),'2;1');
+FILE_NAME('','2023-02-03T21:03:39',(),(),'IfcOpenShell v0.7.0-07ee62eb9','IfcOpenShell v0.7.0-07ee62eb9','');
+FILE_SCHEMA(('IFC4'));
+ENDSEC;
+DATA;
+#1=IFCWINDOWLININGPROPERTIES('0KDBqXun5ECAJL0nrYkMld',$,$,$,$,1.,$,$,$,$,$,$,$,$,$,$);
+#2=IFCWINDOWTYPE('0mTxiq4EvF09FRitqatWTO',$,'WindowType',$,$,(#1),$,$,$,$,$,$,$);
+ENDSEC;
+END-ISO-10303-21;
diff --git a/src/ifcopenshell-python/test/fixtures/rules/pass-lining-properties-None-None.ifc b/src/ifcopenshell-python/test/fixtures/rules/pass-lining-properties-None-None.ifc
new file mode 100644
index 0000000000..ce9a03aed0
--- /dev/null
+++ b/src/ifcopenshell-python/test/fixtures/rules/pass-lining-properties-None-None.ifc
@@ -0,0 +1,11 @@
+ISO-10303-21;
+HEADER;
+FILE_DESCRIPTION(('ViewDefinition [CoordinationView]'),'2;1');
+FILE_NAME('','2023-02-03T21:03:39',(),(),'IfcOpenShell v0.7.0-07ee62eb9','IfcOpenShell v0.7.0-07ee62eb9','');
+FILE_SCHEMA(('IFC4'));
+ENDSEC;
+DATA;
+#1=IFCWINDOWLININGPROPERTIES('28587KCHn5nOtS14mudQ45',$,$,$,$,$,$,$,$,$,$,$,$,$,$,$);
+#2=IFCWINDOWTYPE('1KvP7IY7D8aBiPWa0yrcu2',$,'WindowType',$,$,(#1),$,$,$,$,$,$,$);
+ENDSEC;
+END-ISO-10303-21;