Intent

Explicitly describe the cardinality of a relationship or an event.

Motivation

Software engineers care about measurements, both measurements captured by software solutions and measurements of the solutions themselves. As a consequence, software solution designs need to include information about instance populations, including constraints, limits, thresholds, order, storage sizing, etc.

So, the description of relationships between instances must consider their cardinality: how many instances of each type participate in a relationship? Definite articles, indefinite articles, and indefinite pronouns offer hints about cardinality. However, where practical, explicit cardinality should be sought for problem descriptions and usage requirements.

Applicability

Use a limiting adjective when

• you discover a statement describing a measurable state,
• you discover a statement describing a transitive event, or
• you discover a statement expressing a relationship between instances.

Considerations

Limiting adjectives supply (or indicate the need for) quantitative information about subjects and objects, including number, order, degree, etc. Their presence indicates quantitative areas of a conceptual model that should be explored and specified more concretely during object-oriented analysis. Specific numbers that characterize the bounds on relationships should be obtained from domain experts, solution users, business managers, and governors. For example, are the relationships:

1,
0..1,
0..n,
1..n, or
some other interval?

The following table provides a schema for the kinds of limiting adjectives frequently found in human discourse and the questions that elicit them.

Question	Quantity	Examples
What portion?	Partition	1 / 3
Which?	Ordinality	1st, 2nd, 3rd
How many?	Cardinality	1, 2, 3
How many times?	Iteration	20 times
	Multiplication	20 fold
How much?	Degree	close – closer – closest
Whether?	Affirmation	always, every, …
	Negation	none, never, …
	Doubt	maybe, …

Consequences

You can use a clause summary when a limiting adjective appears in statement about an activity or a relationship. You can use a condition description when a limiting adjective appears in a condition.