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Date: Tue, 2 Mar 2021 17:41:18 +0100 (CET)
From: Roland Lutz <rlutz AT hedmen DOT org>
To: "karl AT aspodata DOT se [via geda-help AT delorie DOT com]" <geda-help AT delorie DOT com>
Subject: Re: [geda-help] Re: file format things
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On Tue, 2 Mar 2021, karl AT aspodata DOT se [via geda-help AT delorie DOT com] wrote:
> Roland Lutz:
>> The solution I favor would be to differentiate between "line width 
>> zero" which, as you explained, means the thinnest line width supported 
>> by the output device (or "no line" in the case of a filled closed 
>> path), and "there's no line width set, use the default width".
>
> The usual solution to "use default", sentinels etc. is to use an illegal 
> value, like -1, NULL, '\0', etc. For a line width, -1 would be suitable. 
> You "cannot" use zero, since mathematically, a line do have a width of 
> zero.

Sounds sensible.  This is still technically a file format change, though, 
since older schematics would otherwise be interpreted as having infinitely 
thin lines.