Section for XRI authority cref resolution

["Drummond Reed" <drummond.reed@onename.com>]

Following is my proposed text for the brief discussion of resolving
cross-references in XRI authorities. (As proof of why we need to add
this, I was surprised how long it took me to think it through. It's
really quite trivial, but the novelty of cross-references as an
identifier construct is what could trip up implementers without simple
guidance like this.)

This would go in as section 3.2.6 right after the Examples section (sort
of like a footnote to the Examples) and right before the User Relative
XRIs section.

Resolving Cross-References in XRI Authorities
A sub-segment within an XRI authority segment may be a cross-reference
(see sections 2.1.1.4 and 2.1.2). Resolving a cross-reference is
identical to resolving any other sub-segment because the cross-reference
is considered opaque. In other words, the value of the cross-reference
(including the parentheses) is considered the literal value of the
sub-segment for the purpose of constructing the Next Resolution URI as
described in section 3.2.4.
For example, when resolving "xri:@:a:b:(.c.d)/f", if the "b" sub-segment
resolves to a Next Authority URI of "http://example.com/xri-authority/";,
then the Next Resolution URI would be
"http://example.com/xri-authority/:(.c.d)", because "(.c.d)" is the
literal value of the entire cross-reference.

Comments?

=Drummond