UMLR — Presentation option for return parameter for operation type are incomplete

Section 7.3.36 Operation, under Presentation Options explains notation options for expressing the return value of an Operation. The example is:

toString(): String

means the same thing as

toString(return: String)

This should also be the same as:

toString(return result: String)

That is, the default name of the return parameter is "result". This is to be consistent with OCL's reference to the result of an operation in a post condition, and to allow a behavior to be able to refer to a return parameter by name.