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From: "Nicklas Karlsson (nicklas DOT karlsson17 AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
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Subject: Re: [geda-user] A fileformat library (DRC clearance value storage)
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Precedence: bulk

> ...
> I would argue that the DRC definitions / design intent capture should
> probably be designed to have the capability of standing alone from the
> PCB layer geometry design file (even if they can also live inside it
> too). We'll need a data-model, as well as (probably) an on-disk
> representation / encoding of that information.

I would say DRC clearance and copper width should be stored in the netlist. As separate data structure where values are given for the nets would of course also work.

> ...
> This is an interesting area for some design work... start to think of
> how all these design rules can be formally defined. How would (ideally
> all of) PCB's existing design rules be represented in this format?

For a given net there would a need to know clearance distance to each other net. If for a net there where a default clearance and it where possible to add a list of clearance values to other nets, clearance distance to each other net would be known. If it works for one net it could be simply be applied for each other net. It would be much simpler to work with if there where net classes or similar but I think they could be implemented more or less as a variable.

To store copper width for a net should not be a problem but it would also be good with copper width possibility for copper width per segment. I think it would also be useful with support for a named variable instead of giving the value directly.


Nicklas Karlsson