An operation reference denotes the execution of an operation by an entity. The operation must be declared as one of the entity operations according to a specific format.
An operation_reference has the following form:
UCEd recognizes the regular form of present formation; the addition of 's' to the infinitive, as well as exceptional cases ending in 'es'.
As an example, ``validates the user identification'', ``validates her user identification'' are valid operation_references given operation ``validate user identification''.
Notice that UCEd doesn't verify the English correctness of sentences therefore ``validates the a its user identification'' would also be accepted.
In other words as soon as the concept operation has been recognized, any other following word is irrelevant.
For instance, given the operation declaration ``validate user identification'', ``validates the user identification with the Branch'' is an operation_reference with action_participant specification ``with the Branch''.