On 04:08 PM 21/11/2001 +1300, Wayne Trow said:
>Hi All
>I have placed a line on the top layer, 1mil thick and made it a keepout
>line (in its property dialog box). Why, therefore, it is flagged as a width
>constraint error when it is a "line" and a "keepout line" at that !
>Are lines and tracks the same on signal layers?
>Sorry - my cheese has almost completely fallen of my cracker !

There is no difference between a line and a track once placed.  The only 
difference is the "smarts" that are applied *as the track is being 
placed*.  Tracks pick up net names of things they touch when first placed 
and are subject to the min-max design rule.  Lines don't have these smarts 
when first placed.

Placing a line frees it from the on-line DRC but it will still be caught by 
the batch DRC.

I think you have stumbled on an oversight, I would almost call it a bug 
(but not quite).  The problem is that there is no method of setting a 
min/max width rule with a scope that targets keepout tracks - you can't 
select by object kind in the width design rule.  There would seem to me to 
be two possible hacks to get rid of this DRC problem.  One is messy and the 
other relies on another oversight.

1) You could add min/max rules with Region scope and carefully select 
regions that encompass your keepout, (yuk yuk yuk!), or
2) Keepout tracks still seem to keep a net assignment, so add dummy 
KeepoutNet to the design, assign all your keepout tracks to this dummy net, 
then use a min/max rule with net (or netclass) scope to allow thin tracks 
only for thaose objects connected to that dummy net.

Method 2  is better but may not work with a future release as really 
keepout tracks do not need a net assignment, but hopefully Protel will 
realise the problem and add Object Kind (with at least Keepout as an 
option) to the min/max rules scopes, or explicitly provide reliable support 
for such dummy nets.  This use of a dummy net is another example where some 
"special" nets such as "Free-Net" to extend the current "No-Net" and 
special netlist/sych directives such as "Don't delete during synchronizing" 
would bear some careful thought and implementation.

Wayne - it seems to me you  may not be having the best of days today...
Ian Wilson

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