Fact form vs. guidance form

When you write a rule or advice in English or Dutch, you can choose between fact form and guidance form.

A proposition that has fact form is a proposition without a modal element. It presents something as factual,structural, unchangeable, not a matter of behaviour. You can always add "by definition” to a statement in fact form without changing its meaning. A typical verb in these statements is the verb is.

A proposition that has guidance form is a proposition that contains a modal element. It presents something as a necessity or obligation that people must follow, but could violate.

What are modal elements?

The chief modal elements in English are must and may.

A proposition can have multiple conditions but always has 1 conclusion. The conclusion is worded in the main clause. Must and may (if present) accompany the main verb, ie., the verb in the main clause.

Example

In this example, the main clause is the part of the sentence before if. The main verb is offered. The modal element is must:

A client must be offered a free upgrade if a car of the requested car group is not available.

There are a number of alternatives to must and may, notably impersonal verbs such as it is necessary that…, it is possible that….

USoft recommends

USoft recommends reserving fact form for facts, definitions, and all statements not under business jurisdiction.

USoft recommends using guidance form for business rules and advices that people can violate.

Examples of fact form

Germany is a country in the Euro zone.

Sandra Berrington works for the Danish government.

These statements are facts. They are statements about instances.

Water freezes at 0° C.

A body at rest will stay at rest unless acted on by an outside force.

The low VAT percentage in France is 10 %.

These statements are what SBVR calls structural rules. The first two are laws of nature (the second was formulated by Newton). The last is structural because it is under jurisdiction of the French government, not the owner of the business rules.

A stayover is the fact that a client spends a night in an accommodation.

This is a definition. It defines a nominalisation (stayover) of a binary fact type (client spends night in accommodation). The interesting thing about definitions is that owners always express them in fact form, thus indicating that for them, they are a given, an immutability.

Examples of guidance form

A client must be offered a free upgrade if a car of the requested price group is not available.

A passenger who boards an aircraft but have a valid ID.

These rules express necessity or obligation. They are behavioural business rules.

A client may be offered a free upgrade if a car of the requested price group is not available.

A new client does not need to supply an IBAN number.

These statements express possibility, absence of obligation, permission. They are advices.

Conclusion

Each time you write a statement in USoft Studio …

… use fact form if you are stating a fact, a definition, or some rule that is definite, structural, a given, out of control of the rule’s owner, in short: if you can add "by definition” to the statement without changing its meaning.

… use guidance form if you are stating a business rule or advice that people can follow, that takes freedom away from them (business rule) or states that no freedom is taken away from them (advice).