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Trailing-Edge - PDP-10 Archives - BB-PBQUC-BM_1990 - help/ctrlu.hlp
There are 3 other files named ctrlu.hlp in the archive. Click here to see a list.
CTRL/U

Erases the current command line.  On hard-copy terminals, cancels  the
command and prints three Xs at the end of the command line.