Hi Sebastian, thanks for your help

Nice idea! Here is what I have so far.
I open some mp3s.
Sort by Filename (Ascending).
Edit > Select all files.
Right-click on the first file in the list > Export the checksums to a text file
md5.txt with the following script:
CODE
$loop(%_filename%)%_md5audio%
$loopend()
Then I import them back by Right-clicking the first file again (while they are all still selected)
Convert -> Text file - Tag
Using the format string
%isrc%As you see, the Convert -> Text file - Tag function will pull the checksums from
md5.txt into the ISRC field.
This works, and I can verify it with your script above, by changing %field_containing_hash% to %isrc% and exporting to
verify.txt.
Have I done it the best way? Or is there another way which doesn't involve exporting and importing the fields back in.
I tried creating a custom action but it didn't seem to work. It just wrote %_md5audio% in the field instead of the actual checksum.
Any other ideas?
Thanks a lot!