Remove text from tag, keep numbers

[blackfiction]

Hi, I am pretty new at this and can not figure out how to remove all text before the numbers. I have a tag called OPUS, which contains text and a number.
I would like to have

1. a OPUSSORT tag which only contains numbers.
   For example;
   opus = T. 65
   opussort would be 65
   opus = BWV 1003a
   opussort would be 1003

2. a OPUSNUMBER tag which contains the numbers and the text thereafter.
   For example;
   opus = T. 65
   opusnumber would be 65
   opus = BWV 1003a
   opusnumber would be 1003a

Hope someone can help me with writing the action codes for these 2,
Thanks

[ohrenkino]

@blackfiction

BWV 1003a

Try an action of the type "Format value" for OPUSSORT with
Format string: $regexp(%opus%,.*?(\d+.*),$1)

Try an action of the type "Format value" for OPUSNUMBER with
Format string: $num($regexp(%opus%,.*?(\d+.*),$1),1)