Re: [xri] Version Control Commit by willnorris

[Will Norris <will@willnorris.com>]

FYI, the final wording I went with:

> The <Expires> element contains a time value which specifies the instant at and after which the document has expired and SHOULD NOT be used. The value MUST be expressed in UTC form, as specified in Section 1.5.3, “Time Values”, and MUST NOT use fractional seconds.
> 
> The semantics of this element apply to the metadata available in the XRD document and are independent of the caching semantics of any transport protocol used to retrieve the document. If present, any cache expiration date specified by the transport protocol SHOULD NOT be later than the time instant indicated by the <Expires> element.