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Date: Tue, 12 Aug 2014 13:50:52 -0700
From: Dave Curtis <davecurtis AT sonic DOT net>
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To: geda-user AT delorie DOT com
Subject: Re: [geda-user] rs-274x nits
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Reply-To: geda-user AT delorie DOT com

On 08/12/2014 11:46 AM, Dave Kerber wrote:
>> -----Original Message-----
>> From: Dave Curtis [mailto:davecurtis AT sonic DOT net]
>> Sent: Tuesday, August 12, 2014 1:51 PM
>> To: geda-user AT delorie DOT com
>> Subject: [geda-user] rs-274x nits
>>
>> 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.
>
> I don't see any conflict there.  #1 is saying that *when processing* you
> must ignore line breaks, but it is recommended to put them in for
> readability.  Your example of splitting G-codes, etc, certainly does NOT
> improve readability.'

So, then it is your interpretation that a correct RS-274X parser should 
not reject G-codes (and other lexical units) that have been split by 
CR/LF's?

>
> #2 is saying to put line blocks where they will improve readability, just
> not at random spots in a data block.
>
>
>>
>> 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
>>
>>
>