diff --git a/basyx/aas/model/aas.py b/basyx/aas/model/aas.py
index b53a423c0..c99efc594 100644
--- a/basyx/aas/model/aas.py
+++ b/basyx/aas/model/aas.py
@@ -112,7 +112,7 @@ class AssetAdministrationShell(base.Identifiable, base.UniqueIdShortNamespace, b
     def __init__(self,
                  asset_information: AssetInformation,
                  id_: base.Identifier,
-                 id_short: base.NameType = "NotSet",
+                 id_short: Optional[base.NameType] = None,
                  display_name: Optional[base.MultiLanguageNameType] = None,
                  category: Optional[base.NameType] = None,
                  description: Optional[base.MultiLanguageTextType] = None,
diff --git a/basyx/aas/model/concept.py b/basyx/aas/model/concept.py
index 07472b9f9..89a8e9b83 100644
--- a/basyx/aas/model/concept.py
+++ b/basyx/aas/model/concept.py
@@ -60,7 +60,7 @@ class ConceptDescription(base.Identifiable, base.HasDataSpecification):
     def __init__(self,
                  id_: base.Identifier,
                  is_case_of: Optional[Set[base.Reference]] = None,
-                 id_short: base.NameType = "NotSet",
+                 id_short: Optional[base.NameType] = None,
                  display_name: Optional[base.MultiLanguageNameType] = None,
                  category: Optional[base.NameType] = None,
                  description: Optional[base.MultiLanguageTextType] = None,
diff --git a/basyx/aas/model/submodel.py b/basyx/aas/model/submodel.py
index b85e59d3c..7ca7d70f4 100644
--- a/basyx/aas/model/submodel.py
+++ b/basyx/aas/model/submodel.py
@@ -122,7 +122,7 @@ class Submodel(base.Identifiable, base.HasSemantics, base.HasKind, base.Qualifia
     def __init__(self,
                  id_: base.Identifier,
                  submodel_element: Iterable[SubmodelElement] = (),
-                 id_short: base.NameType = "NotSet",
+                 id_short: Optional[base.NameType] = None,
                  display_name: Optional[base.MultiLanguageNameType] = None,
                  category: Optional[base.NameType] = None,
                  description: Optional[base.MultiLanguageTextType] = None,
diff --git a/test/adapter/xml/test_xml_deserialization.py b/test/adapter/xml/test_xml_deserialization.py
index 263413239..4a473d2d4 100644
--- a/test/adapter/xml/test_xml_deserialization.py
+++ b/test/adapter/xml/test_xml_deserialization.py
@@ -258,7 +258,6 @@ def test_duplicate_identifier(self) -> None:
         <aas:assetAdministrationShells>
             <aas:assetAdministrationShell>
                 <aas:id>http://acplt.org/test_aas</aas:id>
-                <aas:idShort>NotSet</aas:idShort>
                 <aas:assetInformation>
                     <aas:assetKind>Instance</aas:assetKind>
                 </aas:assetInformation>
@@ -267,7 +266,6 @@ def test_duplicate_identifier(self) -> None:
         <aas:submodels>
             <aas:submodel>
                 <aas:id>http://acplt.org/test_aas</aas:id>
-                <aas:idShort>NotSet</aas:idShort>
             </aas:submodel>
         </aas:submodels>
         """)
diff --git a/test/compliance_tool/files/test_demo_full_example.json b/test/compliance_tool/files/test_demo_full_example.json
index 4e4a4cccd..3f57abc1a 100644
--- a/test/compliance_tool/files/test_demo_full_example.json
+++ b/test/compliance_tool/files/test_demo_full_example.json
@@ -225,7 +225,6 @@
             ]
         },
         {
-            "idShort": "NotSet",
             "modelType": "AssetAdministrationShell",
             "id": "https://acplt.org/Test_AssetAdministrationShell_Mandatory",
             "assetInformation": {
@@ -254,7 +253,6 @@
             ]
         },
         {
-            "idShort": "NotSet",
             "modelType": "AssetAdministrationShell",
             "id": "https://acplt.org/Test_AssetAdministrationShell2_Mandatory",
             "assetInformation": {
@@ -1655,7 +1653,6 @@
             ]
         },
         {
-            "idShort": "NotSet",
             "modelType": "Submodel",
             "id": "https://acplt.org/Test_Submodel_Mandatory",
             "submodelElements": [
@@ -1805,7 +1802,6 @@
             ]
         },
         {
-            "idShort": "NotSet",
             "modelType": "Submodel",
             "id": "https://acplt.org/Test_Submodel2_Mandatory"
         },
@@ -3202,7 +3198,6 @@
             ]
         },
         {
-            "idShort": "NotSet",
             "modelType": "ConceptDescription",
             "id": "https://acplt.org/Test_ConceptDescription_Mandatory"
         },
diff --git a/test/compliance_tool/files/test_demo_full_example.xml b/test/compliance_tool/files/test_demo_full_example.xml
index e326a6b93..188a95a07 100644
--- a/test/compliance_tool/files/test_demo_full_example.xml
+++ b/test/compliance_tool/files/test_demo_full_example.xml
@@ -215,7 +215,6 @@
       </aas:submodels>
     </aas:assetAdministrationShell>
     <aas:assetAdministrationShell>
-      <aas:idShort>NotSet</aas:idShort>
       <aas:id>https://acplt.org/Test_AssetAdministrationShell_Mandatory</aas:id>
       <aas:assetInformation>
         <aas:assetKind>Instance</aas:assetKind>
@@ -243,7 +242,6 @@
       </aas:submodels>
     </aas:assetAdministrationShell>
     <aas:assetAdministrationShell>
-      <aas:idShort>NotSet</aas:idShort>
       <aas:id>https://acplt.org/Test_AssetAdministrationShell2_Mandatory</aas:id>
       <aas:assetInformation>
         <aas:assetKind>Instance</aas:assetKind>
@@ -1527,7 +1525,6 @@
       </aas:submodelElements>
     </aas:submodel>
     <aas:submodel>
-      <aas:idShort>NotSet</aas:idShort>
       <aas:id>https://acplt.org/Test_Submodel_Mandatory</aas:id>
       <aas:kind>Instance</aas:kind>
       <aas:submodelElements>
@@ -1672,7 +1669,6 @@
       </aas:submodelElements>
     </aas:submodel>
     <aas:submodel>
-      <aas:idShort>NotSet</aas:idShort>
       <aas:id>https://acplt.org/Test_Submodel2_Mandatory</aas:id>
       <aas:kind>Instance</aas:kind>
     </aas:submodel>
@@ -3041,7 +3037,6 @@
       </aas:isCaseOf>
     </aas:conceptDescription>
     <aas:conceptDescription>
-      <aas:idShort>NotSet</aas:idShort>
       <aas:id>https://acplt.org/Test_ConceptDescription_Mandatory</aas:id>
     </aas:conceptDescription>
     <aas:conceptDescription>
diff --git a/test/compliance_tool/files/test_demo_full_example_wrong_attribute.json b/test/compliance_tool/files/test_demo_full_example_wrong_attribute.json
index e12d885b4..ff04d91a2 100644
--- a/test/compliance_tool/files/test_demo_full_example_wrong_attribute.json
+++ b/test/compliance_tool/files/test_demo_full_example_wrong_attribute.json
@@ -225,7 +225,6 @@
             ]
         },
         {
-            "idShort": "NotSet",
             "modelType": "AssetAdministrationShell",
             "id": "https://acplt.org/Test_AssetAdministrationShell_Mandatory",
             "assetInformation": {
@@ -254,7 +253,6 @@
             ]
         },
         {
-            "idShort": "NotSet",
             "modelType": "AssetAdministrationShell",
             "id": "https://acplt.org/Test_AssetAdministrationShell2_Mandatory",
             "assetInformation": {
@@ -1655,7 +1653,6 @@
             ]
         },
         {
-            "idShort": "NotSet",
             "modelType": "Submodel",
             "id": "https://acplt.org/Test_Submodel_Mandatory",
             "submodelElements": [
@@ -1805,7 +1802,6 @@
             ]
         },
         {
-            "idShort": "NotSet",
             "modelType": "Submodel",
             "id": "https://acplt.org/Test_Submodel2_Mandatory"
         },
@@ -3202,7 +3198,6 @@
             ]
         },
         {
-            "idShort": "NotSet",
             "modelType": "ConceptDescription",
             "id": "https://acplt.org/Test_ConceptDescription_Mandatory"
         },
diff --git a/test/compliance_tool/files/test_demo_full_example_wrong_attribute.xml b/test/compliance_tool/files/test_demo_full_example_wrong_attribute.xml
index d9270489c..3d1a67d96 100644
--- a/test/compliance_tool/files/test_demo_full_example_wrong_attribute.xml
+++ b/test/compliance_tool/files/test_demo_full_example_wrong_attribute.xml
@@ -215,7 +215,6 @@
       </aas:submodels>
     </aas:assetAdministrationShell>
     <aas:assetAdministrationShell>
-      <aas:idShort>NotSet</aas:idShort>
       <aas:id>https://acplt.org/Test_AssetAdministrationShell_Mandatory</aas:id>
       <aas:assetInformation>
         <aas:assetKind>Instance</aas:assetKind>
@@ -243,7 +242,6 @@
       </aas:submodels>
     </aas:assetAdministrationShell>
     <aas:assetAdministrationShell>
-      <aas:idShort>NotSet</aas:idShort>
       <aas:id>https://acplt.org/Test_AssetAdministrationShell2_Mandatory</aas:id>
       <aas:assetInformation>
         <aas:assetKind>Instance</aas:assetKind>
@@ -1527,7 +1525,6 @@
       </aas:submodelElements>
     </aas:submodel>
     <aas:submodel>
-      <aas:idShort>NotSet</aas:idShort>
       <aas:id>https://acplt.org/Test_Submodel_Mandatory</aas:id>
       <aas:kind>Instance</aas:kind>
       <aas:submodelElements>
@@ -1672,7 +1669,6 @@
       </aas:submodelElements>
     </aas:submodel>
     <aas:submodel>
-      <aas:idShort>NotSet</aas:idShort>
       <aas:id>https://acplt.org/Test_Submodel2_Mandatory</aas:id>
       <aas:kind>Instance</aas:kind>
     </aas:submodel>
@@ -3041,7 +3037,6 @@
       </aas:isCaseOf>
     </aas:conceptDescription>
     <aas:conceptDescription>
-      <aas:idShort>NotSet</aas:idShort>
       <aas:id>https://acplt.org/Test_ConceptDescription_Mandatory</aas:id>
     </aas:conceptDescription>
     <aas:conceptDescription>