How does Blue Ocean apply Reg SHO Rule 201?
Short sales at or below the best bid are canceled unless marked exempt.
For symbols that qualify under Reg SHO Rule 201, Blue Ocean cancels short sale orders priced at or below the Blue Ocean best bid.
The cancel message includes Cancel Reason 21004=12 (NonCompliantPrice).
If an order is marked Short Sale Exempt, it is accepted and processed without cancel.