Please use the "Published By" field when "P.A.I." is credited that way, also when it is mentioned without a specific credit. If a release states "© P.A.I." please use the "Copyright (c)" field.
See also:
P.A.I. is not a label, nor a Rights Society, but an abbreviation that means "Propriétaire Actuellement Inconnu" ("Currently Unknown Owner"). Generally, it is found on records where authors/composers are not affiliated with SACEM, unknown, not registered or are pending registration. It is thus basically the same as and should be treated the same way on Discogs.