Handling multiple topic tags in Subject lines

Do you know if “topic tag” is used in an RFC or something other semi-official documentation? I do like it better than “blob” which was taken from an RFC as far as I can recall :)

The specifiers.plist file is very tricky to change, but I think the following replacement of the subject parser would make “blob” into a multi-value header, but I cannot really recall where MailMate might assume that it's a single value:

{
    parsers = {
        subject = {
            header = "subject";
            // Note the non-ASCII colon (\uFF1A - a full width colon) which is used by some Chinese messages.
            specifierRegexFormatString = '(?x)
                ^\s*                          # Whitespace
                ((?:\s*${MmSubjectPrefixRegexp}[:：])+)?  # Prefix including things like "Re: Re[5]:".
                \s*                           # Whitespace
                ((?:\[([^\[\]]+)\]\s*)+)?     # Subject blob, e.g., "[TxMt]"
                \s*                           # Whitespace
                ((?:\s*${MmSubjectPrefixRegexp}[:：])+)?  # Prefix including things like "Re: Re[5]:".
                \s*                           # Whitespace
                (.*)$                         # Subject body
                ';
            specifierCaptures = {
                1 = { specifier = "prefix"; };
                2 = { specifier = "topics"; parsers = ( "topic" ); canBeImplicit = :true; };
                3 = { specifier = "prefix"; };
                // 4 = { specifier = "blob"; };
                4 = { specifier = "body"; type="noTabs"; parsers = ( "words" ); };
            };
        };

        topic = {
            specifierRegex = '\[([^\[\]]+)\]';
            specifierCaptures = {
                1 = { specifier = "blob"; };
            };
        };
    };
}

Let me know when and how it breaks and I'll see if I can eventually make this default behavior. And maybe use “topic” instead of “blob” as the specifier name.