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Date: Tue, 12 Aug 2014 10:51:10 -0700
From: Dave Curtis <davecurtis AT sonic DOT net>
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Subject: [geda-user] rs-274x nits
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Reply-To: geda-user AT delorie DOT com

I'm trying to interpret the gerber format specification document 
authored by Ucamco.

1. On page 35 it says:
The line separators CR and LF have no effect; they can be ignored when 
processing the file. It
is recommended to use line separators to improve human readability.

2. On page 36 it says:
It is recommended to add line separators between data blocks for 
readability. Do not
put a line separator within a data block, except after a comma separator 
in long data blocks.
The line separators have no effect on the image.


3. on page 40, talking about closing parameter blocks it says:
The ‘%’ must immediately follow the ‘*’ of the last data block without 
intervening line separators.
This is an exception to the general rule that a data block can be 
followed by a line separator.

#3 is clear enough.

#1 and #2 seem to be in conflict.  A strict reading of #1 would say that 
CR and LF should simply be expunged, and that CR/LF could even split 
G-coded, numbers, etc., like this:
G
03
X
123
*
Which seems odd, but is a result of strict reading of #1.   But is in 
conflict with the advice of #2.

It's easy enough to comply with the advice of #2 while writing.  But if 
reading RS-274X, should CR/LF's that split lexical units be ignored? 
Although I realize that even if legal, I doubt if anyone writes gerber 
that way.

-dave