There is actual professional disagreement about the max hoist mark
which is found on some, but certainly not all sailboats.
I spoke to my loft about it and typically the black band is just a
piece of tape, showing maximum hoist for the sail that is sold with the

boat.

Why keep trying to save your ass on this one dimwit. The above
statement is untrue and a real laugh if you claim pros back you up.
A black band is put on a mast to indicate the 'P' dimension or in
other words the max hoist for the mainsail. The boat designer/rig
designer determine these dimensions. It is not just a piece of tape to
indicate max hoist for one sail. Your looking dumber with every post
on this topic.