Activity diagram - how to show several objects that have passed between two actions?

Question

Background

I have one action ( action_a ) that calls an operation ( operation_x ) for another action ( action_b ).

The operation_x parameters are as follows:

action_b.operation_x( param_1, param_2 ) 

I am trying to determine how to document the parameters passed in UML activity diagrams.

Option 1

Can I use a comment?

Option 2

Another option might be to use activity parameters, but doesn’t it seem correct to display two flows from action_a for one operation call?

Question

How can I show multiple transferred objects?

Answer 1

Option 2 is close, but the edges coming out of action_a are wrong, and I don't think it is legal to show the call and data in the same diagram. See my other answer .