# A signed-off spec is still a guess
Delivery · diagnostic · https://build-here.africa/book/chapters/05-04-signing-off-a-spec-does-not-make-it-right.html

## The symptom

A document describes the expected result and the constraints. It has been signed off. A new observation contradicts one of its assumptions.

## The signal

Separate what is required, what was verified, and what is still assumed. Then take the contradiction to whoever signed it off.

## What's going on

A signed-off specification is an agreement about what people believed when they signed it. It does not make the assumptions true. Building and use test them, and some fall.

A document specifies a choice of time slot for sign-up. The team assumes it will make signing up easier. At the first trial, some people do not understand the times offered. The document is signed off. It is also wrong on that point. It needs an answer: a better explanation or a different choice.

Some requirements come from a commitment, a legal obligation or an operating constraint. Contrary feedback does not cancel them. Tell the two apart before you propose a change.

Do not diverge quietly. Bring the facts and the options to whoever signed off, and get the document updated. A document that does not follow reality becomes a source of mistakes for the next person.

## Check this

In a working document, add the assumption that matters most:

> We assume that ...
> We will check it by ...
> If it does not hold, we will ...

When the feedback comes, update the document, whether the assumption held or not.

## To discuss

Which signed-off document holds an assumption that use has already disproved?