netclass.clearance

What it is ¶

netclass.clearance(class, mm) yields the copper-to-copper spacing a net class DECLARES its nets should route at, in millimetres, one row per class that states one. A class that states none yields no row, which is a meaningful fact rather than a gap: that field then cascades to a lower-priority class.

For hardware engineers ¶

This is the number you typed into Board Setup for that class, read back. Query it to confirm the engine sees the constraints you set.

There is no conformance check on this one yet. Clearance IS checked today, but by a purpose-built Go rule against a universal fabrication floor (0.127mm), which is a different question: that rule asks whether the board is manufacturable, this relation says what the project itself demanded.

For software engineers ¶

Keyed by CLASS, not by net, and there is no cascaded per-net counterpart for this quantity. Only net.declared_track_width and net.declared_via_drill are derived, because only those two have a board-tier actual to be compared against (WS3-111 scope). Do not join this to net.netclass and treat the result as a per-net limit: a net in several classes matches several rows, and resolving which one wins is the cascade this relation has deliberately not done for you.

Go projector ¶

netClassDefFacts in stdlib/relations/facts.go walks Model.NetClassDefs(), the ir.Constraint nodes of kind netclass, and parses the clearance param. Populated in the I/O layer by kicad.AnnotateNetClassDefs from the sibling .kicad_pro net_settings.classes[] (WS3-111).

Absence is not a pass ¶

Only a KiCad project read populates this. An EDIF netlist, an IPC-2581 board, a bare .kicad_sch, and a KiCad project that defines no classes all leave it empty. has_netclass_defs is the marker that separates those cases, and it is deliberately distinct from has_netclass: membership and definitions are independent blocks of net_settings, so a project can assign nets to a class it never defined.

Datalog ¶

Every class and its declared value:

netclass.clearance(?class, ?mm) => ?class, ?mm