Okay, then custom field, not struct.
I meant on a thread op. For instance I always add the meaning of the oftentimes Japanese/Yamataigo thread title at the top of my post like so:
((OOC Note: KaiyΕ means ocean.))
If there were an OOC field I would use that instead and it would no longer clutter the RP. I think this would help when a JP is posted as a standalone thread too to put authorship, but it wouldn't help plots like yours that have JPs strewn throughout the thread, sadly.
These wouldn't be places for discussions, just small notes that the thread author wants to convey to readers quickly, even those that aren't players and wouldn't have already checked the OOC.