diff --git a/modeling/model_configuration/classes.attributes.json b/modeling/model_configuration/classes.attributes.json
index 3c171ca..19c7040 100644
--- a/modeling/model_configuration/classes.attributes.json
+++ b/modeling/model_configuration/classes.attributes.json
@@ -138,6 +138,17 @@
     "id": "3T-SBOM-EMS-Artifact-Document-referencedArtifacts",
     "reverseName": "document"
   },
+  {
+    "class": "Document",
+    "name": "referencedDocuments",
+    "description": "The elelement(s) capturing references to other documents, to be used for referenced artifacts, relationships, ...",
+    "type": "3T-SBOM-EMS-Artifact-ExternalDocumentRef",
+    "multiplicity": "*",
+    "aggregation": "shared",
+    "package": "Artifact",
+    "id": "3T-SBOM-EMS-Artifact-Document-referencedDocuments",
+    "reverseName": "document"
+  },
   {
     "class": "Document",
     "name": "signature",
@@ -149,6 +160,35 @@
     "id": "3T-SBOM-EMS-Artifact-Document-signature",
     "reverseName": "document"
   },
+  {
+    "class": "ExternalDocumentRef",
+    "name": "identifier",
+    "description": "The identifier of the document, unique within the namespace.",
+    "type": "http://www.omg.org/spec/UML/20131001/PrimitiveTypes.xmi#String",
+    "multiplicity": "1",
+    "package": "Artifact",
+    "id": "3T-SBOM-EMS-Artifact-ExternalDocumentRef-identifier"
+  },
+  {
+    "class": "ExternalDocumentRef",
+    "name": "namespace",
+    "description": "The namespace of the identifier of the document.",
+    "type": "http://www.omg.org/spec/UML/20131001/PrimitiveTypes.xmi#String",
+    "multiplicity": "1",
+    "package": "Artifact",
+    "id": "3T-SBOM-EMS-Artifact-ExternalDocumentRef-namespace"
+  },
+  {
+    "class": "ExternalDocumentRef",
+    "name": "signature",
+    "description": "The elelement capturing the optional signature of the document.",
+    "type": "3T-SBOM-EMS-Artifact-Signature",
+    "multiplicity": "0..1",
+    "aggregation": "composite",
+    "package": "Artifact",
+    "id": "3T-SBOM-EMS-Artifact-ExternalDocumentRef-signature",
+    "reverseName": "document"
+  },
   {
     "class": "AbstractArtifact",
     "name": "name",
@@ -234,7 +274,7 @@
     "class": "ReferencedArtifact",
     "name": "referenceDocument",
     "description": "Reference to documents that detail the referenced artifact.",
-    "type": "3T-SBOM-EMS-Artifact-Document",
+    "type": "3T-SBOM-EMS-Artifact-AbstractDocument",
     "multiplicity": "*",
     "package": "Artifact",
     "id": "3T-SBOM-EMS-Artifact-ReferencedArtifact-referenceDocument"
diff --git a/modeling/model_configuration/classes.json b/modeling/model_configuration/classes.json
index b2ca3d9..2c627aa 100644
--- a/modeling/model_configuration/classes.json
+++ b/modeling/model_configuration/classes.json
@@ -7,15 +7,36 @@
     "id": "3T-SBOM-EMS-Artifact-Element"
   },
   {
-    "name": "Document",
+    "name": "AbstractDocument",
     "package": "Artifact",
     "generalization": "Element",
+    "description": "This class is the abstract parent of all the classes representing the Software Bill of Material document:",
+    "compositionDescription": [
+      "The document themselves,", 
+      "The references to external documents."],
+    "id": "3T-SBOM-EMS-Artifact-AbstractDocument"
+  },
+  {
+    "name": "Document",
+    "package": "Artifact",
+    "generalization": "AbstractDocument",
     "description": "This class represents the Software Bill of Material document. Its function is dual:",
     "compositionDescription": [
       "Clearly identify the piece of software under consideration,", 
       "Be referenced to attach additional pieces of information pertaining to the considered piece of software."],
     "id": "3T-SBOM-EMS-Artifact-Document"
   },
+  {
+    "name": "ExternalDocumentRef",
+    "package": "Artifact",
+    "generalization": "AbstractDocument",
+    "description": "This class represents references to external Software Bill of Material documents. They can be needed:",
+    "compositionDescription": [
+      "To hint at documents detailing ReferencedArtifact elements,", 
+      "To be used in Relationship elements,", 
+      "..."],
+    "id": "3T-SBOM-EMS-Artifact-ExternalDocumentRef"
+  },
   {
     "name": "AbstractArtifact",
     "package": "Artifact",