UC Role of Invoke Precede

[hmppwork]

Hello,

What is the role of Invoke and Precede in a Use Case diagram?

[RoyC]

I have beefed up the Help on the Use Case toolbox pages to include the following text:

'Invokes and Precedes relationships are defined by the Open Modeling Language (OML). They are stereotyped Dependency relationships; Invokes indicates that Use Case A, at some point, causes Use Case B to begin, whilst Precedes indicates that Use Case C must complete before Use Case D can begin.'

Note that the actions of the source element in an Invoke do not have to complete before the target element actions start. And in a Precedes, the actions of the source element do not necessarily invoke the actions of the target, but the target cannot start unless the source has completed.

[hmppwork]

Ok thank you