net.external

What it is ¶

net.external(net) yields one row per net the read flagged as possibly continuing onto something it did not cover: a net joined by a name-based mechanism (a global label, a power symbol) whose other ends may live in files or sheets the read never opened. It is a read-gap marker, not a topology fact.

It is about read scope, not sheet membership. A net that spans ten sheets of a fully-read design carries no net.external marking, because “which sheets does this net touch” is derivable topology. net.external marks only nets where the read itself may be incomplete.

For hardware engineers ¶

A row here means: what the tool sees on this net is not proof of what the board has on it. There may be more pins, more sources, more loads on a sheet the read did not reach. So a rule that would fire on incomplete connectivity (a decoupling-cap-missing or crystal-load check) suppresses itself on an external net rather than report a violation it cannot stand behind. During a review you query it to see where the read is admitting a gap.

For software engineers ¶

This is the silence-is-not-coverage marker. Absence of a connection on an external net is not evidence of no connection; the read simply may not have covered the far end, the way a partial index cannot prove a symbol is unreferenced. Rules use it as a negative guard: fire only where the read is known-complete. The relation is a projection over Nets() filtered on the external net attribute (netgraph.AttrExternal), so rows are 1:1 with flagged nets, and an empty result means the read is complete and the guard is a no-op.

Go projector ¶

netExternalFacts in check/facts.go walks Model.Nets() and emits a row for each net whose Attributes[netgraph.AttrExternal] is "true". The attribute is stamped by the netgraph solver (internal/netgraph/irout.go) on a by-name net whose other ends may sit in unread files, and cleared once a complete read resolves it (it becomes global instead). One row per external net; empty when the read is complete.

Datalog ¶

List every net the read flagged as a possible read gap:

net.external(?n) => ?n

Use it as a caveat filter: single-connection nets that are genuinely single-pin, excluding the ones that only look isolated because the read did not cover their far end:

net.pin_count(?n, 1), not net.external(?n) => ?n