The type, ordering, and multiplicity of the argument and result pins of a CallAction shall be the same as the corresponding Parameters. Source Unified Modeling Language 2.5.1
The argument Pins of a CallAction are matched, in order, to the sublist of input Parameters, while the result Pins are matched, in order, to the sublist of output Parameters. Source Unified Modeling Language 2.5.1
Behaviors and Operations have totally ordered lists of owned Parameters, and these Parameters are matched to Pins on a CallAction using that ordering. Source Unified Modeling Language 2.5.1
