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Last update: 20 April,2001

								1003.2-92  #66

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	Interpretation Number:	XXXX
	Topic:			more
	Relevant Sections:	5.18.7 p 567 ll2903-2905

Interpretation Request: (Defect Report)
-----------------------

Subject: Extended Description for More

I would like an interpretation of the Extended Description for More
outlined in IEEE Std 1003.2-1992 section 5.18.7., p. 568, Line
2903-2905.

The standard appears unclear as to the effect of a multibyte character
followed by a backspace character; if the backspace is written
_directly_ to the terminal, then the terminal driver/hardware could
treat the backspace in one of two ways.

1. Move the cursor left one screen column;
2. Move the cursor left one character (so that subsequent characters
overwrite).

The standard appears to expect case 2, though the use of "generally"
does imply some exceptions and therefore permit case 1.  Who handles
moving the cursor one charcter left - more or the terminal?  If the
answer is the terminal then should POSIX.2 be corrected since behaviour
outside their control is being mandated?

Would it be possible to replace lines 2903 - 2905 with:

- Other <backspace> sequences are written to the terminal so that for
each <backspace>, the terminal's cursor is moved left the width of the
character preceeding the terminal's cursor until the left margin is
reached.  The affect of a <backspace> when the cusor is at the left
margin is undefined.

If you require clarification of this request, or more information,
please do not hesitate to contact me at (519) 884-2251.  If you
prefer email, you may reach me at alex@mks.com; please refer to
"more.6295" in your message.

Alex White

IEEE Interpretation for 1003.2-1992 
-----------------------------------



paragraph 1) 

The definition of backspace is on page 16 lines 266-267. Although there is 
no rationale for backspace in more, the rational for backspace in fold applies 
here as well.  The rationale for fold in section E.4.25 page 908 lines 
6357-6368.   

paragraph 4) 

Neither one, it's the application producing the text file that more is asked 
to display.

Rationale for Interpretation:
-----------------------------
None.
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