Follow-up on PE 25, 28

We need some minor change to the language at lines 182-184 to reflect 
the inclusion of metadata and non-profiles like the SAML URI binding
in the various conformance tables.

We could replace "by means of a triple taken..." and replace it by "by 
referring to self-contained features such as Metadata and the SAML URI 
binding, or 
by means of a triple taken. [unchanged]".