PE2 and <ArtifactResolutionService>

Just a followup on PE2,

For this particular case, the requirement is declared in 
SAMLProf., Section 4.1.6., Line 639:

"If the request or response message is delivered using the HTTP
Artifact binding, the artifact issuer MUST provide at least one
<ArtifactResolutionService> endpoint element in its metadata."

It's the only required use of MD I could find, btw.

--Nick