[GreenKeys] How are BREAK encoded?

[John Nagle]

    You cannot encode BREAK on paper tape, either 5 bit
or 8 bit.  In Baudot, all ones is the BLANK key.
In ASCII, it's NULL.

    BREAK is a period of SPACE longer than one character.
It's distinguished by having SPACE during the stop bit
time.  Most UARTs recognize this.  The mechanical
teletypes do not; they just "run open", outputting
BLANK or NULL until the period of BREAK ends. Then
there's one garbage character.  Then normal operation
resumes.

				John Nagle