The 'u' GGEP Extension
======================

Name: u
Where: Query, Query Hit (per File Entry)
Status: Experimental (as tagged in HUGE specifications)
Date: Mon Jul 16 13:47:36 MEST 2003
Format: Text of the URN, without the leading "urn:" prefix
COBS-Encoding: Never
Deflate: Maybe
Revision: $Id: u 3569 2003-07-16 12:11:06Z rmanfredi $

[Those specs written by Raphael Manfredi from the HUGE specifications]

The "u" extension is used to transport URNs in their natural textual form,
with all the necessary escaping.  There is never any NUL bytes in URNs,
so it is never necessary to COBS-encode those.

The payload of "u" is the actual URN but without the leading "urn:" prefix.
For instance, to actually transmit the value:

	urn:sha1:PLSTHIPQGSSZTS5FJUPAKUZWUGYQYPFB

in the "u" extension, one would only put the following in the payload:

	sha1:PLSTHIPQGSSZTS5FJUPAKUZWUGYQYPFB

In order to send common hashes, better use the "H" extension, which is more
compact.  The "u" extension is only meant to be used to send other kind
of URNs, such as the ones that cannot be summarized by a single binary value.

If the URN you want to send does not start with "urn:", i.e. if you cannot
strip any "urn:" prefix out of it, then you MUST NOT use the "u" extension.
