How to use $meta() function - examples

Hare Krishna.

Dear sirs,

I am not able to understand how to use $meta(x) function.

My aim is:
I have 5500 mp3 files with different tags. For some files subtitle tags are same but genre tags are different. I want to display all files having genre say "blues" and the files connected to these files having same subtitle as these files although their genre may differ. To sum up -- group of files having same subtitle and having genre = "blues" genre in at least any one of files

Help will be appreciated.

Thankyou,
damodara das

The $meta() function as nothing to do with your problem but lets you address individual fields if you have several fields of the same type/name.

Back to your problem or that what I think it is:
You can set a filter
%genre% IS Blues OR %subtitle% HAS xyz

MP3tag does not compare files and does not know anything about a "connection" between files.
If you have a grouped your files so that all the genres are in one folder, you can easily load only that folder and set the genre for these files in the tag panel.

Mp3tag Filter: SUBTITLE HAS "some subtitle name" AND GENRE IS "blues"

DD.20170416.1213.CEST