When you add variables to an Action, you have to declare a data type. The available types are displayed in the Type list. This list includes all the
Page Messages for the application, as well as all the input and output messages for custom code and web services. It also contains simple types, as well as all the complex types defined in the
Data Model.
The message variable for the Action does not appear in the variables section. You can access the data in the
message variable by using sets to set variable parts to the values in the corresponding
message variable parts.
If you’re going to pass the variable into a Page, the data type for the variable should match the
Page Message for that
Page. Similarly, if you’re going to pass the variable into a service, the data type should match the service’s input message.