[common] A {flag}, usually in hardware, that selects between two
(usually quite different) modes of operation. The connotations are
different from {flag} bit in that mode bits are mainly written during
a boot or set-up phase, are seldom explicitly read, and seldom change
over the lifetime of an ordinary program. The classic example was the
EBCDIC-vs.-ASCII bit (#12) of the Program Status Word of the IBM 360.
[glossary]
[Reference(s) to this entry by made by: {bit}{bit bashing}{bytesexual}{flag}]