Greetings,
  I have made one relatively minor modification to the pear CVS file:
pear/Text_Wiki/Text/Wiki/Parse/Mediawiki/Url.php


Verbose Explanation:
====================
  This simple change consists of appending a single entry to the schemes
array which makes it possible for Mediawiki to parse links which use the
following syntax:
  [//pear.php.net Pear::Homepage]

The W3C document which discusses the resolution of partial URLs can be found
at http://www.w3.org/Addressing/URL/4_3_Partial.html.  The portion of this
document which is relevant for the purposes of this patch is the following
statement:
``If the scheme parts are different, the whole absolute URI must be given.
Otherwise, the scheme is omitted, ..``

The URL definition (from the official W3 specifications) seems to support
legitimacy of the aforementioned document as it states that it does not
define the resolution of fragmented or partial URLs. This document can be
found at http://www.w3.org/Addressing/URL/url-spec.txt.  The specific quote
is:
``Fragment identifiers and partial URLs are not involved in the basic
   URL definition.``


Examples:
=========
  If we were presently at https://example.com/index.php, and this page
renders a Mediawiki link which has the wiki form of
"[//images.example.com/hello.jpg]", the specification would dictate that the
URI resolve to https://images.example.com/hello.jpg.

  As a supplementary example, if we were presently at
http://example.com/index.php, and this page renders a Mediawiki link which
has the wiki form of "[//images2.example.com/hello2.jpg]", the specification
would dictate that the URI resolve to http://images2.example.com/hello2.jpg.


Testing Methodology:
====================
  I am basically proposing that we add the ability to omit the scheme from a
url to be able to inherit from the proper document.  I have verified that
this works as described in the examples above through testing on my own
apache webserver.  My tests concluded that if one is to use a url in an
xhtml document which has the form of:
"//fully.qualified.ip.org.dns.entry/resource/specific_one", the url scheme
gets inherited from whatever scheme the document was accessed with (I tested
that this works for both Internet Explorer 6 and Firefox 1.5).  Testing was
performed by executing queries equivalent to the examples and then checking
the logs to verify the appropriate scheme had been used each time. 


Optional Reading:
=================
  And for those of you who may be interested in this kind of thing, I found
http://www.w3.org/DesignIssues/Axioms.html to be an interesting read
regarding URI schemes (even though the document appears to be a decade old
by now and is not official).


Final Thoughts:
===============
This is my first patch, so please forgive the general excessiveness and/or
any wrongdoing on my part.  I have put forth my best effort to follow the
protocol outlined at http://pear.php.net/manual/en/contributing.patches.php.
I welcome constructive feedback regarding how I can improve any future
patches.

Thanks,
Jay