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From:	Dave Kerber <dkerber AT warrenrogersassociates DOT com>
References:	<53EA540E DOT 9000609 AT sonic DOT net>
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Date:	Tue, 12 Aug 2014 14:46:47 -0400
Message-ID:	<2aabf5abd73cc057e4a0193bf4a2d101@mail.gmail.com>
Subject:	RE: [geda-user] rs-274x nits
To:	geda-user AT delorie DOT com
Reply-To:	geda-user AT delorie DOT com

> -----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.

#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
>
>

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