Another quick question (RE: copying portions of a tag field)

To add to my post:

Basically I want to take a subset of data written into the "comments" field (specifically 'written-by' data gathered from Pone's Discog's script) and copy it to the composer field.

Here is a post that deals with copying...

Regular Expressions

...but I only want a portion of the data.

The typical discogs additional credits format might have something like:

Keyboards - Person 1, Person 2
Producer - Person 1, Person 2
Written-by - Person 1, Person 2, Person 3

I just want to take the "Written-by" data and copy the people over to the "composer" field. I can separate them with a semi-colon using an additional action.

I thought I saw this kind of a post somewhere, but I still cannot find it.