An objective that was a guess, written down as a guess

A service level objective invented in a meeting is a guess, and the useful move is to say so in the document rather than to pretend otherwise.

## Checkout availability

**Objective:** 99.5% of checkout requests succeed, measured
over 30 days.

**Basis:** a guess. we have no historical measurement and
no customer commitment. 99.5% allows ~3.6 hours a month,
which feels tolerable to us and has not been tested with
anybody who pays.

**Review:** 2023-07, with three months of data.

An objective presented as a derived number invites arguments about the derivation; one presented as a starting point invites data. The July review moved it to 99.9% because the measured figure was 99.94% and the guess had been generous, which is a conversation that could not have happened without the first number existing.