HumanCell .org wrote:
At present, the character '+' isn't allowed in article names. Is there any particular reason for this? Would it be easy to change?
Historical reasons: "+" is used in form URL encoding to signify space. Some early versions of our software used this when producing URLs, and we've continued to consume those old links until recently when the ability to use "+" was enabled for Wikimedia's own wikis.
As of MediaWiki 1.6, you can enable the use of "+" by overriding the $wgLegalTitleChars setting. See its entry in DefaultSettings.php for instructions.
Note that a "+" needs to be URL-encoded as "%2b" in order to survive processing in a query string. As with the "&" and "?" characters, this may make it vulnerable to problems when using Apache rewrite rules.
-- brion vibber (brion @ pobox.com)