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Trailing-Edge - PDP-10 Archives - BB-PBQUC-BM_1990 - help/ctrlh.hlp
There are no other files named ctrlh.hlp in the archive.
CTRL/H

Reprints a command line up to  the  field  that  is  in  error.   Type
immediately after the input error message.  Duplicates the function of
the BACKSPACE key.