Modality

Updated 22 Jul 2026

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def
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  indicates whether or not participation in a relationship is mandatory or optional
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values
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  0 — there is no explicit need for the relationship to occur; the relationship is optional
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  1 — an occurrence of the relationship is mandatory
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contrast with Cardinality
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  cardinality describes how many; modality describes whether it must exist at all
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related

Linked references 4