How to list all defined custom metadata fields?

I know for a record I can get its custom metadata via

set theCMD to custom metadata of theRecord

But theCMD will only contain keys for fields which have a non-default value.

How can I find out via Applescript all available fields like they are listed in Preferences -> Data?

The first script in this post lists them all in an AppleScript choose from list. Clicking copies one meta data identifier at a time for pasting into a script.

Should be easy to change the script to do what you want.

Thanks Pete.

If I understand the post correctly it is the first script that collects the metadata fields, and in order to do so it needs to read the metadata plist file, right?