AT&T 6300 Programmer's Manual page 37

Getting Started
Character Deletion
If you accidentally type an extra character in
the line you are entering, then proceed as
follows:
You discover the error.
For example, suppose you typed:
GOTTO_
instead of:
2 To erase the extra T, press Cursor Left, or other cursor
movement keys, to move the cUrsor to the appropriate
position:
GOTTO
3 Press DEL:
GOTQ
4 Move the cursor using Cursor Right:
5 Continue typing
GOTO 1000_
Deleting Part of a Line
To erase a line from the current cursor
position, press CTRL END.
Deleting an Entire Line
To cancel the line you are entering, press ESC
anywhere in the line. It is not necessary to
press CR.
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