subject categories

Hello,

 

As we are trying to update the XSPA XACML profiles, one of the tasks is to support XACML version 3. I noticed that for “subject” attributes, there are now 4 different categories defined in the core. The mandatory category:

urn:oasis:names:tc:xacml:1.0:subject-category:access-subject

and the optional categories:

urn:oasis:names:tc:xacml:1.0:subject-category:recipient-subject

urn:oasis:names:tc:xacml:1.0:subject-category:intermediary-subject

urn:oasis:names:tc:xacml:1.0:subject-category:requesting-machine

 

But the core does not provide any definition or discussion about the differences between these categories. I was wondering if anyone can comment about the differences or refer me to a definition so that we can make a better decision on
 which category to use for which attributes. 

 

Thanks.

 

Regards,

Mohammad