No text, but a visual code

[ololololo]

Perhaps it is of a decorative nature and does not relate to either the Moon or the other Rosettas. Like the same T‑O map next to the supposed Rosetta of Earth.

But I could understand TO Earth attached to Earth rosette to indicate Earth, that seems informative, rather than simply decorative, but what would astrolabe trine attached to "?" indicate? (I don't know what Antonio identifies this rosette as, other than it is not the earth, moon, or fixed stars). Does it relate at all to the thing on the other side of the same rosette?

The connection to Rosette’s turnover is controversial, so I won’t say anything here, because I don’t know
Perhaps this volvelle denotes some abstract “measurement”, “coordinates” or something similar, and it refers either to the nearby Rosette or to all of them at once.
In any case, in the form presented, its significance is either decorative or illustrative.