# Filter based on differing Artist or Composer

**URL:** https://community.mp3tag.de/t/filter-based-on-differing-artist-or-composer/13098
**Category:** Support
**Created:** [February 15, 2012, 11:34pm UTC](https://community.mp3tag.de/t/filter-based-on-differing-artist-or-composer/13098 "2012-02-15T23:34:59Z")
**Posts on this page:** 1
**Showing post:** 9

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### Author: ![pone](https://community.mp3tag.de/user_avatar/community.mp3tag.de/pone/32/272_2.png) [@pone](https://community.mp3tag.de/u/pone)
#### Post date: [March 4, 2012, 10:42am UTC](https://community.mp3tag.de/t/filter-based-on-differing-artist-or-composer/13098/9 "2012-03-04T10:42:53Z")

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It's a filter expression again, as you probably have guessed yourself.

$list() is a undocumented function in Mp3tag. I have no idea why it isn't mentioned in the help files. Here is a very good explanation from DetlevD:  
[Lyrics aus Datei importieren?](https://community.mp3tag.de/t/6888/9)

The $regexp() function around it deletes tge values of the fields and the \<\<\< \>\>\> seperator and leaves only the blank field names wihth a single space after each name.

Use the Tag-Filename Converter if you want to see a preview of the functions (do not press OK):

$list(, \<\<\<,\>\>\>)  
$regexp($list(, \<\<\<,\>\>\>),\<\<\<.+?\>\>\>,)

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