A.7.6 Coupled resource

[idevisser]

GeoDCAT-AP :The target dataset or series SHOULD be preferably referred to by using its unique resource identifier

but

TG Requirement 3.6: metadata/2.0/req/sds/coupled-resource

Links pointing to the online metadata descriptions of data sets provided by the described service shall be given using srv:operatesOn element.

The multiplicity of this element is 0..n.

This property shall be implemented by reference. The xlink:href attribute of each of the srv:operatesOn elements shall contain a URI pointing to the metadata record of the provided data set or data set series.

expecting an unique resource identifier is not realistic

[bertvannuffelen]

@idevisser can you elaborate your comment with an example?

As the linking is done by reference according to your message: there is an identifier.
Is your comment on the uniqueness, the URI representation, or something else?

[idevisser]

The coupled resource contains the URL of the metadata describing the dataset, it does not contain the unique resource identifier as specified in https://github.com/INSPIRE-MIF/technical-guidelines/blob/main/metadata/metadata-iso19139/metadata-iso19139.adoc#3121-unique-resource-identifier.
Although ISO 19119:2016 requires that the target of the srv:operatesOn element (Coupled Resource) is the #MD_DataIdentification class of the linked dataset metadata, due to the different existing metadata implementations, is concluded to allow a more simple implementation of the Coupled Resource linkage, a URI pointing to the metadata record.