A business rules primer
Business rules
A business rule expresses a necessity or obligation. A business rule always takes away some freedom that people in the business would otherwise have.
A business rule contains a business rule keyword. Here are business rule keywords that USoft prefers:
| Business rule keywords (preferred) | ||
|---|---|---|
| must must not | may not | may … only |
Must is usually suitable. If you need a negation, combine it with not (must not).
May expresses necessity or obligation only if combined with either not or only. Only can appear earlier or later in the sentence than may, and other words can appear between the two.
May not in English can also mean "perhaps does not always”. This can be a drawback of this word combination.
Examples
These examples show that USoft Studio automatically provides Necessity: captions to the left of business rules:
The last example is not the best choice. It is harder to read than the others because of the double negative (not and without).
Advices
An advice expresses a possibility or permission. It says that some course of action is open. It never takes away any freedom.
An advice contains an advice keyword. Here are advice keywords that USoft prefers:
| Advice keywords (preferred) | |
|---|---|
| may(without not and without only) | does not need to |
Make sure that in combination with may, you do not also use not or only, or else the statement will turn into a business rule instead.
So, you cannot use not to express that people have the option to not do something. But you can use does not need to.
Examples
The top example shows that USoft Studio automatically provides the Possibility: caption to the left of advices.
The bottom example shows that the caption for does not need to is: Other:
Alternative keywords
Natural language offers a wealth of alternatives to the preferred keywords in this article. We find there is never a really good reason to use other keywords. Should is popular, especially with British speakers, as a milder alternative to must, but in a collection of business rules, should can introduce uncertainty or polite vagueness.
The following keywords can be of service, and are also recognised by USoft Studio as business rules keywords:
Alternative keywords
| it is necessary that | it is not necessary that |
| it is obligatory that | it is not obligatory that |
| it is possible that | it is not possible that |
| it is permitted that | it is not permitted that |