Renumbering a list hides the gap

We keep a numbered list of rules about how screens should behave — fifteen of them, written down because a rule you can point at by number gets followed and a rule described in a paragraph gets argued about.

The list arrived in two pieces, and the first piece we received started at six. Somebody wrote a note next to it saying that one to five did not exist, and for three weeks nobody looked for them, because the note said not to. They existed. They had always existed. The note telling people not to look was the only thing stopping anyone finding them.

When they turned up, the tempting move was to tidy the whole thing into a clean run of fifteen. We did not, deliberately. The first five kept the numbers one to five and the original ten kept six to fifteen, which is exactly the arrangement that made the gap visible in the first place.

What renumbering costs

Imagine your prep list has nine steps and step four goes away, because the supplier now delivers that item ready portioned. Good news. You renumber five to nine as four to eight and print a fresh copy.

Now consider everything that referred to step six. The laminated card on the bench. The training pack the new starter read last week. The note in the allergen folder that says see step six. The chef who has said step six out loud four hundred times. Every one of those now points at a step that used to be seven, and nothing anywhere announces the change. There is no error message. The new sheet looks tidier than the old one.

The failure is silent and it is delayed. It shows up weeks later as somebody confidently doing the wrong thing, having followed a reference correctly.

Keep the gap, write why

The alternative costs one line. Step four stays in the list, and instead of a method it says: no longer needed, the item arrives portioned, since March.

Now every old reference still resolves. Somebody who learned the list last year looks for four, finds four, and reads why it is empty. Somebody who wonders whether a step was lost gets an answer instead of a suspicion. And the list carries its own history, which is the cheapest documentation anybody ever wrote.

This is why numbers ought to be treated as addresses rather than positions. A position describes where a thing sits in a queue and changes whenever the queue changes. An address identifies one thing for ever, and things you can name for ever are the things you can talk about reliably.

The same rule, everywhere it hurts

Table numbers. Moving the covers around and renumbering the floor is a week of wrong deliveries. Add letters, leave gaps, retire a number rather than reusing it. A retired table number is a small confusion once. A reused one is a wrong plate every few shifts for as long as anybody remembers the old layout.

Item codes. When a dish comes off, the code retires with it. Handing last season's code to a new dish means last season's sales are now filed under something that never sold, and no report will ever tell you, because the report cannot know.

Training modules and policies. If module three is folded into module two, say so in three. Nobody reads the change note. Everybody reads the thing they went looking for.

Order numbers. Never reuse one inside a day, even after a void. Two things with one name is an argument you cannot settle afterwards, and the person you are arguing with is holding a receipt.

The renumbering always looks like tidying. It is the one kind of tidying that destroys information, and the information it destroys is the kind nobody misses until they need it.