diff --git a/codes/IdsProtocolSpecification.ttl b/codes/IdsProtocolSpecification.ttl
new file mode 100644
index 00000000..b7b29eae
--- /dev/null
+++ b/codes/IdsProtocolSpecification.ttl
@@ -0,0 +1,35 @@
+@prefix owl: <http://www.w3.org/2002/07/owl#> .
+@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+@prefix dct: <http://purl.org/dc/terms/> .
+@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+@prefix ids: <https://w3id.org/idsa/core/> .
+@prefix idsc: <https://w3id.org/idsa/code/> .
+
+
+idsc:IDS-REST
+    a ids:IdsProtocolSpecification  ;
+    rdfs:label "IDS REST" ;
+    rdfs:comment "The REST specification of the IDS interactions."@en ;
+    rdfs:seeAlso <https://github.com/International-Data-Spaces-Association/path/to/ids/rest/spec/> ;
+.
+
+idsc:IDS-CP
+    a ids:IdsProtocolSpecification  ;
+    rdfs:label "IDS-CP" ;
+    rdfs:comment "The IDS-CP specification of the IDS interactions."@en ;
+    rdfs:seeAlso <https://github.com/International-Data-Spaces-Association/path/to/idscp/spec/> ;
+.
+
+idsc:QUERY
+    a ids:IdsProtocolSpecification  ;
+    rdfs:label "Query" ;
+    rdfs:comment "Queries conforming to IDS specifications."@en ;
+    rdfs:seeAlso <https://www.w3.org/TR/sparql11-overview/> ;
+.
+
+ idsc:MULTIPART
+    a ids:IdsProtocolSpecification  ;
+    rdfs:label "IDS over Multipart" ;
+    rdfs:comment "The Multipart Messages implementation of the IDS interactions."@en ;
+    rdfs:seeAlso <https://github.com/International-Data-Spaces-Association/path/to/multipart/spec/> ;
+.
diff --git a/model/communication/Endpoint.ttl b/model/communication/Endpoint.ttl
index e0434a00..989b21c7 100644
--- a/model/communication/Endpoint.ttl
+++ b/model/communication/Endpoint.ttl
@@ -41,7 +41,11 @@ ids:GenericEndpoint
     rdfs:comment "Generic endpoints describe non-IDS-specific endpoints, e.g., to integrate external services."@en ;
 .
 
-
+ids:IdsProtocolSpecification
+    a  owl:Class ;
+    rdfs:label "Protocol Specification" ;
+    rdfs:comment  "List of all defined Protocol Specifications, for instance IDS-CP or IDS over Multipart."@en ;
+.
 # Properties
 # -------
 
@@ -98,6 +102,12 @@ ids:outboundPath
     rdfs:range xsd:string;
     rdfs:comment "Relative path used for outbound communication via this endpoint, i.e., output messages and faults only."@en.
 
+ids:apiSpecifiation  a  owl:ObjectProperty  ;
+     rdfs:label "follows API specification" ;
+     rdfs:comment  "Declares which endpoint specification is supported by this IDS endpoint." ;
+     rdfs:domain  ids:Endpoint ;
+     rdfs:range   ids:IdsProtocolSpecification ;
+.
 
 ids:appEndpointType
     a owl:ObjectProperty ;