In the rest of phpBB's codebase, $message typically represents either the content of a whole post/pm or the content of an error message so it would be confusing to reuse the name for some local text replacement. This function is called for each match and receives an array of captured substrings (as per [PCRE](http://www.pcre.org/pcre.txt)'s terminology) so I want for $captures. Hope that makes sense.