Read First: Operation Gives the information required to start an operation. This relation is at Operation rather than Method because signature overloading is modelled as a separate operation for each signature. The inputs of the operations must include variables with type of the objects that are used for making requests (see requestsThrough/supportsRequestsFor). Other than that, users have alot of leeway in how input variables are chosen. They may require as few inputs as possible, preferring to calculate other necessary information from those inputs. On the other hand, they may require many inputs, in order to use calculations already made by the event diagrams that are using the operation. As a guideline, users should define an operation's input so that it applies to as general types as possible, and is most generally useful to event diagrams that might call it. This will increase the potential reusability of the operation. See comments at Method.