You can declare a variable to be of a type other than the default types by adding a Schema builder to your model.
When you open the Variable builder call editor, the types defined in the schema appear in the list of available types.
In addition, you can pre-populate the variable with the appropriate XML structure with sample text values for any appropriate elements by clicking the Create Sample Data
button. Creating sample data is useful because you do not have to build up the appropriate structure when you set the value of the variable, you can just set the text values of the individual elements in the structure.
Parent topic: Variable builder