Split info in YEAR field

[Ves]

I have music files that have the following written in the 'YEAR' field

2023\2017-09-29

I'm looking to move the last date '2017-09-29' to the 'RELEASETIME' field.

Tried the following

Also tried split field by separator, format value and guess value but can't understand how to do this.
Which annoys me as I was able to make 4 other action after reading up a bit.

[ohrenkino]

Try an action of the type "Guess value" (if you are on a Mac: Import tag fields)
Source: $meta_sep(year,==)
Target string: %year%==%releasetime%

[Ves]

That solve it for me, thanks!

Would have never made the connection with '$meta_sep' and '=='.

[ohrenkino]

Then == is just a trick to get a probably unique separator between the fields. It has no other special meaning.