Document numbering

Why it matters#

A document number is what makes a document referenceable — in a procedure, in a contract, in an audit finding, in a conversation. Without a stable identifier, documents are referred to by title, titles change, and references stop resolving.

What a scheme should encode#

Enough to be recognisable and no more. Document type and a sequence is usually sufficient; adding department, year and originator produces numbers people cannot read and that become wrong when the organisation reorganises.

The exception is where a standard prescribes it: ISO 19650 naming in construction encodes project, originator, volume, level, type and number precisely because documents cross organisational boundaries and must be identifiable without context.

Gaps are correct#

A sequence with gaps looks like an error and usually is not — a document was created and deleted, or a number was reserved and unused. What matters is that a number is never reused, because a reused identifier makes two different documents indistinguishable in any historical reference.

Systems that "tidy up" gaps by reissuing numbers are actively harmful.

Numbering and titles#

The number identifies; the title describes. Keeping them separate means a document can be retitled without breaking every reference to it, which is exactly what happens when the reference is the title.

When to include a check digit#

Where numbers are transcribed by hand — onto physical files, into another system, over the phone — a check digit catches transposition errors cheaply. Where they are only ever copied digitally it is unnecessary complexity.