Question

How come wiki article titles cannot have colons or @'s?

Answer 1

The message that you get when you try to name a wiki with invalid characters is

Wiki and Article names cannot contain colons or @'s, and they cannot consist entirely of numbers.

I don't know for sure, but I suspect the restrictions have to do with the way the "Insert Link" feature works:

If you type

Wiki    Contact Info        Article with "Contact Info" 
                            headline in this Wiki
        Internal:FAQ        Article with "FAQ" headline in Wiki
                            named "Internal"
        W123             Article #123 in FogBugz

Case    1234             Case #1234 in FogBugz

Project YourProjectName     FogBugz project homepage for 
                            "YourProjectName"

Web     http://example.com  http://www.example.com

Email   Email@Example.com   mailto:Email@Example.com

If you had a wiki article title that contained a colon, when you went to insert a link to it, FogBugz might think you were trying to look for a wiki name/headline pair (e.g. Internal:FAQ)

Likewise, if you had a wiki article with an @ sign, FogBugz might think you were entering an email address.