The Data Integration Service resolves one level of parameter values. The Data Integration Service does not resolve parameter values that are nested within another workflow parameter or variable.
For example, you assign the following workflow parameters these values in a parameter file:
Parameter1 has a value of 3
Parameter2 has a value of 4
Parameter3 has a value of
${par:Parameter1} + ${par:Parameter2}
When you use Parameter3 in an expression or task field, the Data Integration Service does not resolve the nested parameters Parameter1 and Parameter2 to the value of 7. Instead, the Data Integration Service uses the following string value for Parameter3: