What XrefBase covers, and how a claim gets here.

The catalogue in figures

Parts in catalogue

3,601

Manufacturer part numbers the lookup can resolve, each filed under one manufacturer.

Manufacturers

496

Manufacturer records those parts are filed under. Some imported names still await an identity check, so this is not yet a count of distinct companies.

Parts with any recorded relationship

1022.8% of parts

Parts whose lookup returns anything at all, in any of its six groups — from a published replacement to a mating counterpart. Most are context, not substitution claims.

Parts with a published replacement

100.3% of parts

Parts whose lookup returns something under “Published replacements” — the only answer that asserts one part can stand in for another.

Parts with a functional equivalent

00% of parts

Similar function, not a confirmed drop-in. Engineering review is required before substitution.

Aliases recorded

142

Other numbers for the same physical part. An alias is identity, never an alternative.

Obsolete parts recorded

10

Parts whose lifecycle is recorded as obsolete. For 3,591 others no lifecycle is recorded — unknown, not active.

Open Orphans

0

Parts somebody needs an alternative to, still seeking one on the board — open, with a candidate declared, or under review.

Relationships by type

One row per kind of relationship, worded exactly as the lookup words it. Counts are published pairs: a relationship between two parts counts once, whichever end it is looked up from.

Where the coverage is

Each bar is a group’s parts in the catalogue, all on one scale. The fills say how many of those parts have a published replacement, how many have some other recorded relationship, and how many have none — which means not assessed.

• Published replacement
• Relationship recorded, but no published replacement
• Nothing recorded — not assessed

By manufacturer — the 15 largest, then everyone else

By top-level category

Review freshness

Reviewed relationships

10

Reviewed between

5 Sept 2026 – 18 Sept 2026

Next revalidation due

5 Sept 2027

Overdue for revalidation

None

Every reviewed relationship is due a second look on its revalidation date: a manufacturer can withdraw or revise a notice, and a claim nobody re-checks only gets older. The other 168 published relationships carry no review date, and none of them makes a claim: the lookup presents them as context, never as a substitute.

Methodology

How a relationship gets created — cheapest and most certain first

1. 1 · Part-number grammarWhere a manufacturer’s numbering is self-documenting — Deutsch DT and HD are — a parser derives same-series, variant and mating links. It is deterministic, but a grammar is not a manufacturer statement, so these cap at medium confidence and never assert substitution. Where a grammar cannot be verified, no parser runs: TE’s was evaluated and rejected because it would have invented structure.
2. 2 · Manufacturer change noticesA PCN or PDN in which the manufacturer says one part replaces another. Authoritative and public, it is the only source that earns high confidence with a citation. Each is checked by an independent reviewer before publishing and carries a revalidation date.
3. 3 · Alternate designationsOther numbers already embedded in imported part numbers become aliases — the same part under another number, never an alternative to it. Conservative patterns only: a bare slash is usually part of the number.
4. 4 · Specification matchingDatasheet attributes compared within a category to propose functional candidates. Not in use yet: it is the expensive tier, and it waits until the mechanical ones are exhausted.
5. 5 · Reviewed declarationsAn engineer, producer or distributor declares a candidate — against an Orphan or directly — with public documents. It stays a declaration until a reviewer turns it into a candidate relationship, and a separate decision publishes it.

Three rules that do not bend

• A drop-in is published only when verified.High confidence and a public source, enforced by the database rather than by good intentions. A wrong drop-in claim stops a production line.
• A mating part is never an alternative.Counterparts live in their own table so they cannot be returned as one. DT04-3P mates with DT06-3S — the one part guaranteed not to substitute for it.
• Every published claim cites a public source.A private file may point at what to check; only the publicly re-confirmed fact is published, citing the public source. Family, variant and mating links cite nothing further: the part numbers are the evidence.

What “not assessed” means

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