You can create new user variables or assign new values to existing variables in a composition using the <assign>
element.
The <assign>
element used in a composition is identical to that which can be used in an expression, however when used in a composition the SIS disregards the return result of the assignment attempt.
Example
This example shows a composition that invokes one service (VPN), changes the Service Key
parameter of the initial event, then invokes two more services (HomeZone and PrePay) with the modified parameter.