param

What it is ¶

param(mpn, symbol, max) yields one row per parameter of a datasheet spec that joined to a part in the design, keyed by manufacturer part number (mpn) and the parameter’s datasheet symbol (e.g. VDD, VIN, RDS(on)). The third argument is the parameter’s numeric maximum, in that parameter’s SI base unit (volts, amps, ohms) whatever the vendor printed, so a threshold written against it means the same thing across vendors. Join param.unit for the printed spelling. Each row also carries the rendered value range and its test conditions, plus a citation back to the datasheet page and table. One MPN can be shared by several components, so the projector dedupes by MPN and emits each parameter once. A parameter whose unit has no known scale still appears here with its NUMBER absent, and an ordering comparison refuses to bind an absent number against a present one rather than answering by string order (agni issue 165).

This is the datasheet tier of the query surface. It is EMPTY unless agni is run with --params <dir> pointing at a seeded PartSpec corpus. That is skip-not-false-pass by construction: with no datasheet corpus loaded, the relation yields zero rows and every rule that reads it reports not-applicable rather than a false pass.

For hardware engineers ¶

A row is one line off a part’s datasheet: an absolute-maximum, a recommended-operating limit, a rated value, under the test conditions the datasheet stated. The max value is presented, not silently compared. A parameter whose conditions survive only as free text (not structured as eq/min/max) is not machine-comparable, so the tool shows it to you beside its citation rather than auto-checking a design value against it. You query param during a review to see what the datasheet actually claims for a part before trusting a rule that leans on it, or to spot which parts have no extracted spec at all (they simply do not appear).

For software engineers ¶

A PartSpec is the .d.ts type stub for a closed-source dependency: machine-readable claims about a part you cannot see inside, each written against one pinned doc revision and linking back to the prose it came from. param projects those claims into query rows. The design-side identity is component.mpn(ref_des, mpn); param is keyed by the same mpn, so the two relations join on it. That join is the whole point of the tier: it is how a rule crosses from “this net in the design drives R1’s VIN” to “R1’s MPN has an absolute-maximum VIN of 20 V”. Rows are 1:many with a part (one per parameter). Absent means the datasheet corpus was not loaded, or the part has no spec in it, never that the part is fine.

An empty join is not a clean result. component.mpn ⋈ param is an inner join, so a component whose part has no seeded row for the symbol is silently dropped, and the query returns zero rows for the same reason a genuinely-clean design does. Reading that as pass is the SQL bug of treating a LEFT JOIN with a NULL right side as a validated row. A datasheet-backed review item therefore checks whether the symbol is seeded at all and reports needs-data (closer to HTTP 424 Failed Dependency than 404: the check exists, its input is missing) rather than pass. needs-data still counts as covered, because the mechanism is wired and only the value is absent, and that lets an overlay bind a datasheet check before its seed lands and watch it flip to a real verdict once the value arrives (WS3-097). Whether the corpus holds one seeded part or a thousand is only how many rows the table has: the relation is the union of every seeded spec, keyed by MPN, so more seeds mean fewer needs-data items, never a different answer.

Go projector ¶

paramFacts in check/facts.go iterates Model.Components(), reads each component’s MPN via Model.ComponentMPN and its spec via Model.PartSpec, dedupes by MPN, and emits one row per spec.Parameters entry. Value is rendered by rangeText, Conditions by conditionsText, and Cite by citation (document title, page, table or figure, extraction method, confidence); Num is set to the parameter’s Value.Max when present, and surfaces as the max datalog argument. One row per parameter of each joined part. Empty without --params, because the MPN-to-spec map is built only when a param set is loaded, so a design with no matching specs yields nothing.

Datalog ¶

Both queries need --params. List every extracted parameter for each part, as MPN and symbol:

param(?mpn, ?sym, ?max) => ?mpn

Join to the design-side part identity to name the components a datasheet parameter applies to (the bridge a rule like supply-exceeds-abs-max walks to compare a design rail against a datasheet absolute-maximum):

component.mpn(?ref, ?mpn), param(?mpn, ?sym, ?max) => ?ref