It would be useful, if you can place the command $filename(your_filename) everywhere within the script file (not only in the beginning of it). For example you could create m3u files as many as artist / album etc. 
Possible script:
$loop(%artist%,1)
$filename(%artist%.m3u)#EXTM3U
$loop(%_filename_ext%)#EXTINF:%_length_seconds%,$if(%artist%,$if(%title%,%artist% - %title%,%_filename%),%_filename%)
$replace(%_folderpath%%_filename_ext%,%_workingpath%,)
$loopend()
$loopend()
I'm here again.
We could do complete HTML structure in this way by some clicks. 
Any chance to integrate this thing? Please... Maybe in version 3.0? Or I am the only one who would like this feature?
EDIT: OK. I made a little software to split up the file created by MP3Tag into several pieces with the name and path I need. (I should have created 458 m3u files with unique names in special directories manually. I'm reorganizing my sound archives now.)
I realized that this function was requested by milka here.