3 XHE digital signature - one informative, the other normative material

My attention was drawn to this section because of the improper 3.1 without a 3.2.

After reading the text, I suspect it should be:

3. XHE digital signatures

3.1 XML Digital Signatures (Informative)

Using the IETF/W3C XML Digital Signature specification [xmldsig one can add multiple “non-final” signatures or a single “final” signature to the exchange header envelope as the last children of the document element, that is, after the last BIE of the document element. A non-final signature digitally signs all content other than any of the other sibling signature elements that may exist in the document. A final signature digitally signs all content including the other sibling signature elements that may exist in the document.

3.2 XML Advanced Electronic Signature

The schema fragment for Section 5.6.2, “Extension content” included in this distribution provides for using digital signature extensions supporting XML Advanced Electronic Signatures [XAdES (ETSI TS 101 903), when the electronic signing of an exchange header envelope is necessary to satisfy legal and technical requirements. The schema fragment can be modified to accommodate such future extension requirements without impacting on the conformance clauses of this specification.

Reasoning that XML Digital Signatures are used with any XML document and in that regard, your specification doesn't provide any normative guidance.

For XML Advanced Electronic Signature, your specification defines a schema fragment that enables use of XAdES.