As an example, I have seen real estate partnerships acting as the “parent”, and investing in other “subsidiary” partnerships. The income and losses reported by the limited partners of the “parent” would generally be treated as passive.(I am of course ignoring any portfolio income.)
A sale or disposition of a subsidiary partnership would be a capital transaction, and I believe properly treated as a passive capital gain. Information as to the proper tax reporting should be determined by the sponsor and provided to the limited partners. If unknown, contact investor relations to make sure you have the proper information.
Suspended passive losses should net against the passive capital gain. Additionally, a capital loss forward should also net against the passive capital gain.