Trying out Picard. I loaded an mp3 that has a WPAY tag used for a payment link.
But this tag is not being detected in Picard. It is detected in another app I use (Kid3).
WPAY/Payment is also not listed in the dropdown when adding a new tag. Is there a list somewhere of all supported tags out of the box. Thoughts on why this tag seems to be excluded?
Thanks!
Yes, Picard does not know about this tag. There is a detailed list of all tags supported by Picard and how they are saved to at https://picard.musicbrainz.org/docs/mappings/
As to why this is unsupported: You are actually the first person (I am aware of) in the last 11 years I am part of Picard’s development who is asking for support of this tag 
This might give some clue. Also Picard’s main focus was on tags that can either directly be filled with data from MusicBrainz or are so commonly used that they are interesting for plugins. Also a bonus is if a certain tag is available in multiple tag formats (meaning there is some specification for or common usage of a tag name) .
Anyway, there is no reason not to support this tag. You could open a feature request at https://tickets.metabrainz.org/ .
Thanks for the thorough reply.
I will make a ticket for this feature request.
Knowing that I am the only person who has inquired about this tag, I will set my expectations low but hope that it is easily added.
This tag is nice to have to point to donation pages or crypto addresses.
It is reminiscent to the equally under-utilized rel=payment microformat.
Recently, there was some discussion for supporting it for podcasters both on web page and within RSS feeds (my suggestion). The Overcast Podcast app, for example, added support. I think supporting it as an ID3 tag would be a nice companion to these other methods.
Thanks again,
Michael