Addition of new Metadata Placeholder

Hi ohrenkino.
I am using MPEG v3.07. I do not have any field called RHYTHM. Below is the script I am using for Export:

**$filename(rtf,ansi){\rtf1\ansi\ansicpg1252\deff0\deflang1033{\fonttbl{\f0\fswiss\fprq2\fcharset0 Tahoma;}}
\viewkind4\uc1\pard\b\f0\fs32 Mp3tag File Overview\par
\b0\fs20 %_date%\par
\par

$loop(%_filename_ext%)
Title: \b %title%\b0\par
SubTitle: \b %subtitle%\b0\par
Artist: \b %artist%\b0\par
Album: \b %album%\b0\par
Track: \b %track%\b0\par
Genre: \b %genre%\b0\par
Rhythm: \b %rhythm%\b0\par
Comment: \b %comment%\b0\par
Composer: \b %composer%\b0\par
Conductor: \b %conductor%\b0\par
Length: \b %_length%\b0\par
\par
$loopend()
\par
build on %_date%, with \b %_app% - the universal Tag Editor\b0 - http://www.mp3tag.de/en/\par
}t**

In the script, the italicized bold Rhythm is what I am trying to export. I already have it on the Tag Panel.
I am asking if it is possible to add Rhythm to the list of placeholders in the lists:
(Format Strings and Available Placeholders)

Jerry B