This function will strip declared BBCodes and their content away from quoted messages.
[intro]The strip_bbcodes() function and $__BBCODE_NOT_QUOTABLE__ array were developed when a bug occurred with the [hide] BBCode. When one of admin wants to hide his message from common members, but wants to send something to other admins, he can put his message into [hide] bbcode. All was fine, but when message was quoted, using the quote feature in the forum, everything appeared and could be read from the quoted text.[/intro]
So if any of bbcode puts itself to the $__BBCODE_NOT_QUOTABLE__ array it will be stripped.
If some_bbcode must be hidden it is declare in some_bbcode_include_var.php => $__BBCODE_NOT_QUOTABLE__ = "some_bbcode"; then will be auto-stripped by strip_bbcodes() function from quoted message in the forum.