= Support for InterWiki links =

''This is a proposal for implementing #40 and #1414''
''I think it's now ready for testing (see r1912)''

== Definition ==

An InterWiki link can be used for referring to a Wiki page
located in another Wiki system, and by extension, to any object
located in any other Web application, provided a simple URL 
mapping can be done.

== Link Syntax ==

{{{
<target_wiki>(:<identifier>)+
}}}

The link is composed by the targeted Wiki (or system) name,
followed by a column (e.g. {{{MeatBall:}}}),
followed by a page specification in the target.

The target Wiki URL is looked up in a the InterMapTxt wiki page, 
modelled after
[http://www.usemod.com/cgi-bin/mb.pl?InterMapTxt MeatBall:InterMapTxt].

An addition to traditional InterWiki links, where the target
is simply ''appended'' to the URL, 
Trac supports parametric InterWiki URLs:
identifiers {{{$1}}}, {{{$2}}}, ... in the URL
will be replaced by corresponding arguments from a list
made up from the page specification split by the ':' token.

== Examples ==

If the following is an excerpt of the InterMapTxt page:

{{{
= InterWiki Map =

This is the InterMapTxt wiki page,
modelled after the MeatBall:InterMapTxt page.
----
{{{
...
LiveJournal http://livejournal.com/users/
Login http://www.usemod.com/cgi-bin/mb.pl?action=login&p_userid=
MbTest http://www.usemod.com/cgi-bin/mbtest.pl?
MeatBall http://www.usemod.com/cgi-bin/mb.pl?
MetaWiki http://sunir.org/apps/meta.pl?
MetaWikiPedia http://meta.wikipedia.org/wiki/
Mineralienatlas http://www.mineralienatlas.de/lexikon/index.php/
MoinMoin http://moinmoin.wikiwikiweb.de/
...
Trac http://projects.edgewall.com/trac/$1/$2
}}}
}}}

Then, 
 * {{{MoinMoin:InterWikiMap}}} should be rendered as 
   [http://moinmoin.wikiwikiweb.de/InterWikiMap MoinMoin:InterWikiMap]
 * {{{Trac:wiki:InterWiki}}} should be rendered as
   [wiki:InterWiki Trac:wiki:InterWiki].