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R54 / 1:1c

Stem Notation defines zero or one Label Placement Specification

Label Placement Specification is defined for exactly one Stem Notation

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A Stem Notation may or may not specify a text label. In the Starr class diagram notation a generalization arrow has no associated text. In xUML, however, the arrow is accompanied by the UML tag { disjoint, complete }. There seems to be no reason to support multiple labels for a Stem as none of the supported notations require them.

A Label Placement Specification is custom fit to a given Stem Notation. The Shlaer-Mellor c label is associated with any class multiplicity where zero is a possibility, however, the position of that c label could vary since the stem icon size might vary. It is safest just to create a separate placement for each Stem Notation even if many of the position values are identical.