(e) When the methods above do not yield an absolute URI, a base URL of "thismessage:/" MUST be employed. This base URL has been defined for the sole purpose of resolving relative references within a multipart/related structure when no other base URI is specified.
(c) Try to resolve all relative URIs in the HTML content and in Content-Location headers using the procedure described in chapter 5 above. The result of this resolution can be an absolute URI, or an absolute URI with the base "thismessage:/" as specified in chapter 5.
(d) For each referencing URI in a text/html body part, compare the value of the referencing URI after resolution as described in (a) and (b), with the URI derived from Content-ID and Content- Location headers for other body parts within the same or a surrounding Multipart/related structure. If the strings are identical, octet by octet, then the referencing URI references that body part. This comparison will only succeed if the two URIs are identical. This means that if one of the two URIs to be compared was a fictitious absolute URI with the base "thismessage:/", the other must also be such a fictitious absolute URI, and not resolvable to a real absolute URI.
The handling of relative and absolute URIs for matching between body parts have been merged into a single description, by specifying that relative URIs, which cannot be resolved otherwise, should be handled as if they had been given the URL "thismessage:/".
- URI scheme syntax.
- Generic URI. See RFC 3986 for details.
- URI scheme semantics.
- A fictitious URI scheme used for internal processing only, not to appear URIs communicated between applications.