UID ordering

[David Shaw]

On Fri, Feb 16, 2007 at 07:10:36PM +0100, Christian Danner wrote:
> Hello David!
> 
> On Fri, 16 Feb 2007 09:10:55 -0500, David Shaw <dshaw at jabberwocky.com>
> wrote:
> 
> >> Is it possible that the list of a key's user-ids returned by GPG 1.4.6
> >> is reordered and doesn't represent their positions within the key?
> >> What am I missing?
> >
> >Generally, GnuPG tries to put the most recent or primary user ID
> >first, but there are no real requirements that user IDs are in any
> >particular order.  If you want a user ID to be the primary one, you
> >can do that in the --edit-key menu with the "primary" command.
> >
> >David
> 
> Thanks for your kind answer, which unfortunately only raised new
> questions.
> 
> Is there a real indicator for the primary uid defined within the key?
> In the first place I searched for such a flag at the 'uid:...' line,
> but found no information about it in the 'DETAILS' file.

There is.  When you set a primary UID, the self-signature on that UID
is actually remade with a signature subpacket that tags the UID as the
primary one.  Note that if you have any photo UIDs on your key, there
are two different primaries: one for the regular text UIDs, and one
for the photo (aka "attribute") UIDs.

David