Issue: Section 3.2.3 [1]
 - Use of terms strings is semantically incorrect.
-  More RFC[2119] terminology needed for clarity.

Section 3.2.3 [102] states:
”[102]The <RespondWith> element in the request specifies one or more strings included in the request that specify data elements to be provided in the <ds:Keyinfo> element of the response. Each string is a single identifier corresponding to a sub-element of the XML Signature Specification [XML-SIG]<ds:Keyinfo> element  or the private key information defined in  the section Cryptographic Algorithm Specific Parameters below. The XML Signature elements are described here for convenience. The normative reference is the specification [XML-SIG].”

Purposed Text:
[102]The <RespondWith> element allows the sender of a request to specify which data elements MAY be provided in the <ds:KeyInfo> element in the response.   One or more <RespondWith> elements MAY be included in a request where each <RespondWith> element URI value is an identifier than corresponds to either a sub-element of the XML Signature Specification [XML-SIG] <ds:KeyInfo> or the private key information defined in section Cryptographic Algorithm Specific Parameters below.  The XML Signature elements are described here for convenience.  The normative reference is the specification [XML-SIG].

Justification:
(1)Eliminates the term ‘strings’ where URI is required.
(2)Specifies ‘MAY’ for <ds:KeyInfo> sub-element response items, which is accurate.
(3)Disambiguates the element’s value as the identifier.