Coregions in UML

开发者_StackOverflow社区What are coregions in UML sequence diagrams?

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Coregions are used when the sequence of events does not matter, that is they can occur safely in any order.

This is one of the first few pages I found when I searched coregion sequence diagram in Google.

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The coregion is a notational/sytanx choice for representing parallel CombinedFragments the UML 2.2 Superstructure spec (14.3.3) says:

Parallel The interactionOperator par designates that the CombinedFragment represents a parallel merge between the behaviors of the operands. The OccurrenceSpecifications of the different operands can be interleaved in any way as long as the ordering imposed by each operand as such is preserved. A parallel merge defines a set of traces that describes all the ways that OccurrenceSpecifications of the operands may be interleaved without obstructing the order of the OccurrenceSpecifications within the operand.

The answer above is correct this is just more context.

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The UML is specified by the OMG in the two documents (http://www.omg.org/spec/uml): The UML Infrastructure and the UML Supestructure. Whatever documentation may be not official.

In the UML superstructure section 14.3.3 it is said:

A notational shorthand for parallel combined fragments are available for the common situation where the order of event occurrences (or other nested fragments) on one Lifeline is insignificant. This means that in a given “coregion” area of a Lifeline all the directly contained fragments are considered separate operands of a parallel combined fragment.