externalSubjectId PUBLIC_READABLE

[BirgitBoss]

Is your feature request related to a problem? Please describe. The default in the current specificaiton V3.0 is that a specificAssetId is relevant for all. However, there are scenarios where this might be critical and applications may request that the default is "not visible to anybody until stated otherwise".

Describe the solution you'd like Add a predefined external subject ID with name "PUBLIC_READABLE" as a reserved key for externalSubjectIds. Add information that implementations may request to set the externalSubjectId to this subject explicitly. No externalSubjectID would then mean that only the owner of the AAS can see the specificAssetIds

Describe alternatives you've considered

• change default but this would not be downwards compatible

Additional context This issue was raised in the context of Catena-X, standard CX-0002 requests: „On default, the read access to Digital Twins SHOULD be enabled by Digital Twin Registry Solutions to data providers only”