Found this in a old manual, yes i am 50+ :-)

CORRECTION OF ERRORS Errors on punched tape may be corrected in
various ways, depending upon the
type of error and when it is noticed. Three correction techniques are
explained
here.
The easiest correction is for an error which is detected immediately
after the
wrong key has been depressed. In this case, one need only
1. Turn the FEED KNOB on the left side of the punch back one notch.
2. Depress the CODE DELETE lever once.
3. Continue punching by depressing the proper key on the keyboard.
If a wrong key is depressed whose tape code is a portion of the
desired combination,
the operator need only back the tape until the incorrect character is
under
the punch head, and overpunch it with the proper key. This method is
particularly
useful when the error is detected after characters have been punched
beyond the
error. However, it can only be used when the erroneous and correct
tape codes
are related in the proper way. For example, a "6" can be overpunched
on a "O",
"2", or "4", but not on "5" since the tape code for 5 has a punch in
channel 4
while that for "6" does not. 

Harry
> -----Oorspronkelijk bericht-----
> Van: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
> Namens Wouter van Ooijen
> Verzonden: zondag 9 augustus 2009 22:57
> Aan: Microcontroller discussion list - Public.
> Onderwerp: Re: [TECH] language - was [PIC] using BREAK in 'C'
> 
> > It replaces what was there before in the same position on 
> the punched 
> > tape with what could be seen as a "NOP".
> > If my memory doesn't fail me...
> 
> Totally correct. (not surprising, knowing that you are a bit 
> older than my average student)
> 
> -- 
> 
> Wouter van Ooijen
> 
> -- -------------------------------------------
> Van Ooijen Technische Informatica: www.voti.nl consultancy, 
> development, PICmicro products docent Hogeschool van Utrecht: 
> www.voti.nl/hvu
> 
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