Coregions in UML

Question

What are coregions in UML sequence diagrams?

Answer 1

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

This is one of the first few pages that I found when I was looking for a kernel sequence diagram on Google.

Answer 2

. Coregion is the designation / choice of syntax for representing parallel Combined Fragments. The UML 2.2 superstructure specification (14.3.3) states:

Parallel The parameter of interaction with the operator means that CombinedFragment is a parallel merge between the behavior of operands. The appearance of the Specifications different operands can alternate in any case, as long as the order placed by each operand as such is preserved. Parallel merging defines a set of traces that describes all the ways that operands can alternate without interfering with the order of Incident Specification within the operands.

The answer above is correct, it's just more context.

Answer 3

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

Section 14.3.3 of the UML Add-in says:

For the general situation, when the order of occurrence of events (or other nested fragments) on one Lifeline is not significant, there is a conditional reduction for parallel combined fragments. This means that in a given area of ​​the Lifeline core, all directly contained fragments are considered separate operands of a parallel combined fragment.