Index: work/feature_poll/src/progdrc/long
===================================================================
--- work/feature_poll/src/progdrc/long	(nonexistent)
+++ work/feature_poll/src/progdrc/long	(revision 2027)
@@ -0,0 +1,36 @@
+The original/current DRC (Design Rule Checker) applies a set of rules hardwired
+in the C code. A programmable DRC would instead provide C code to do basic
+steps of checking (e.g. "is there at least 4 mil spacing between these
+two objects"?). The actual rules could then be specified using a simple
+scripting language.
+<p>
+As the number of generic C utilitiy functions would grow, a programmable
+DRC would enable the following practical features:
+<ul>
+	<li> different/dynamic minimal copper spacing depending on random factors, like distance to a specific component (e.g. increase requred clearance next to the transformer), per network (e.g. 10 mil to gnd, but at least 15 mil to anything else)
+	<li> checking for keep-away (copper-wise: HV/LV insulation; silk-wise: component spacing)
+	<li> checking star topology grounding
+	<li> "keep this net shorter than 15 mm"
+	<li> check if matched length pairs or buses are really matched within whatever margin (e.g. +-5%)
+	<li> ... or even the number of vias on them are matched
+	<li> check if traces of a differential pairs are really kept close together
+	<li> ensure minimum trace width (high current nets)
+	<li> ensure bypass caps are close enough to the corresponding device
+	<li> microstrip and friends: make sure traces for this net have gnd below them on the next layer (including: no gaps)
+	<li> other layer-related checks like "don't ever route this net on an outer layer"
+	<li> enforce component orientation or layer, e.g. "all these buttons should face south" (the actual wording depends on the initial orientation of the footprint or maybe on a vector defined as a sequence of pin numbers)
+	<li> ensure two components are near or far from each other (e.g. don't place the sensitive opamp too near to the HV section), place this component close to the outline layer
+</ul>
+<p>
+All these not via custom C code hand crafted for each specific use case, but
+because of script fewliners that combine simple checks in the right way. In
+turn, the DRC script can be generated by the netlist tool, from network
+or component attributes, using DRC-script templates. This lets the user
+extend the DRC to cover new cases without having to change or recompile
+pcb-rnd code.
+<p>
+<i>Compatibilty:</i> mainline pcb wouldn't understand the drc scripts;
+mainline pcb would ignore or even remove drc scripts from save files. The design
+could still include old-style drc parameters so the simplest checks could
+be performed by mainline pcb.
+
Index: work/feature_poll/src/progdrc/short
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--- work/feature_poll/src/progdrc/short	(nonexistent)
+++ work/feature_poll/src/progdrc/short	(revision 2027)
@@ -0,0 +1,2 @@
+Programmable DRC
+