What a Book of Criteria is, and why every rule has a source

It is where your way of deciding is put in writing. Every knowledge professional applies rules they rarely spell out: when to take on a project, what to ask a new client first, which sign makes them wary of a proposal, when to advise waiting. The Book of Criteria captures them one by one, in sentences anyone can read.

In Digital Twin by Legathum, every twin has its own Master Brain, the brain that holds everything it knows. The Book of Criteria is the layer of that brain that holds the rules you decide by, written in plain language, reviewed and approved by you, each one with its source.

The idea behind it is simple: anyone can copy a face; copying someone's judgement is the hard part. And judgement can only be copied once it has been written down.

Every rule has the same parts, so they all read the same way and can be reviewed one by one.

Of all these parts, the one most often forgotten and the one that matters most is the source.

Because a rule with no source is an opinion nobody can check. The source makes three things possible that do not exist without it.

The first is review. When a rule looks odd, the source shows where it came from: a particular session, one of your documents, a case you described. You can go back to it and decide whether the rule still holds.

The second is correction. Rules change because you change your mind, because the market moves or because a new case shows there was an exception. With the source in view, correcting a rule is an informed decision rather than a crossing-out.

The third is trust. A digital twin speaks in your name. Knowing that what it knows comes from rules with a known origin is what allows you, and then your clients, to trust it.

It enters as a candidate and only counts once a person reviews it. No rule approves itself.

There are four steps. First, candidate rules arrive in the draft of the Book, for example from your documents or from the sessions in which you explain how you work. Second, each one is marked as reviewed once someone has read it and accepted it. Third, when the draft is ready, it is activated: it becomes the Book in force, with a note explaining what changes and why. Fourth, the previous version stops applying, and there is a record of which version was in force at each point.

That activation note matters. It is the signature of whoever puts the criteria into force, and the answer to the question "since when have we decided this way?".

A knowledge base holds what you know; the Book of Criteria holds how you decide with what you know. Both are part of the twin's brain, but they do different jobs.

ISO 30401 sets requirements for establishing, maintaining, reviewing and improving a knowledge management system in an organisation. The same logic applies to the Book: it is not enough to store what you know; you have to review and improve it methodically.

Because you, your team and, if need be, your client have to be able to read the rule. A rule written in jargon can only be understood by whoever wrote it, and that defeats the review.

ISO 24495-1, published in 2023, sets out governing principles and guidelines for writing plain language documents, and states that they also apply to technical writing. For a rule in the Book, that means one decision per rule, explicit conditions, concrete verbs and no unexplained abbreviations.

Yes. The Book in force can be exported in full, as Markdown or YAML, two text formats that open in any editor. The brain belongs to you, and the Book is the part of it you can download today.

Exporting it is useful for more than leaving: to review it on paper, to share it with a partner or to use it as an internal manual of how you work.

Today, the Book is the foundation of your twin's brain: what you have reviewed and approved is what counts as your judgement. In development: the twin applying those rules in conversation and saying which rule each answer comes from.

In the meantime, the Book is valuable in its own right. Writing your rules forces you to think about how you decide, and almost every professional who does it finds rules they applied without knowing, and one or two they no longer agree with.

• Today: every twin has its own Master Brain, with a Book of Criteria of rules in plain language, reviewed and approved, each one with its source.
• Today: rules enter for review, are activated by version with a note, and the Book in force exports as Markdown or YAML.
• In development: the twin applying the rules in conversation and naming the rule behind each answer.
• In development: exporting the whole brain, not just the Book.