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  1. OMG Issue

UML23 — default multiplicty of association ends are defined more than one

  • Key: UML23-18
  • Legacy Issue Number: 13477
  • Status: closed  
  • Source: Change Vision ( Michael Chonoles)
  • Summary:

    In the infrastructure 6.2.1 it says

    If no multiplicity is shown on an association end, it implies a multiplicity of exactly 1.

    However, in

    8.3.3 Associations

    The opposite ends of associations connected to the class are also listed in the same way. The sub clause states if the association is derived, or if it is a specialization of another association. The multiplicity of an association end is suppressed if it is ‘*’ (default in UML).

    It appears that the default is 1 and the default is also * which is confusing.

    I believe it should be clarified something like this.

    When an association is shown as an attribute/property, the default multiplcity is the same as the default attribute/property multiplictty (1)

    When an assocation or attribute is shown as a association (that is, on the end of a line), the default multiplicity should be

  • Reported: UML 2.2 — Wed, 11 Feb 2009 05:00 GMT
  • Disposition: Resolved — UML 2.3
  • Disposition Summary:

    The default multiplicity is always 1.
    This text appears only in the section describing the structure and conventions used by the specification itself. Superstructure has the following similar text:
    The “Attributes” sub clause of a concept description lists each of the attributes that are defined for that metaclass. Each attribute is specified by its formal name, its type, and multiplicity. If no multiplicity is listed, it defaults to 0..*.
    Which is inconsistent with the Infrastructure text for Attributes:
    The multiplicity of the attribute is suppressed it defaults to „1? (default in UML). In practice both documents are now explicit about all association multiplicities, and suppress only attribute multiplicities of [1].

  • Updated: Fri, 6 Mar 2015 20:58 GMT