Bit Position Indicator

The Bit Position Indicator is the period. This generally appears in "Flag Affected" fields of bit-breakdown diagrams, meaning that that specific bit is unaffected. It is a placeholder meant to take up space, and is distinct from a question mark or space character, which in reverse engineering indicate "don't know what happens to this bit."

Reference

• Appendix C-1 of Book I of the official Super Nintendo development manual