SHOULD statements in conformance clause belong to specification body

SHOULD statements have little meaning in a conformance clause the goal of which is to draw a clear line for conformance.
For example:
"An implementation SHOULD support the XML encoding"
should rather be stated in the specification body, the section of which would then be referred by the conformance clause in a meta-level statement like "An implementation is conforming to the Server profile if it satisfies all mandatory requirements in section 123".