Oracle VM admin asks for page 83 id in a LUN

I have 2 Unity 400 arrays and synchronous replication is in place for a couple of LUNs.

From Unity 1 I'm replicating a LUN to Unity 2 and also the other way around.

I have an Oracle VM cluster attached to each of the two arrays and the Oracle VM administrator is asking me about a page 83 item which seems to be different on each LUN / Replica LUN pair. He says the page 83 item needs to be identical on each Primary / Secundary LUN pair.

I don't know where to set this data and one of the posts I can find on this is one from 2008 which addresses a Symmetrix and some SPC-flag.

Does anyone know what this page 83 thing is about?