[IBM] The error code displayed on line 25 of a 3270 terminal (or a PC
emulating a 3270) for various kinds of protocol violations and
"unexpected" error conditions (including connection to a {down}
computer). On a PC, simulated with `->/_', with the two center
characters overstruck.
Note: to appreciate this term fully, it helps to know that "broken
arrow" is also military jargon for an accident involving nuclear
weapons....
[glossary]