Custom Service Variables can be defined and used within a Service call flow. The variables are available to the whole Service XML including any sub plans.
These values can persist for the duration of the call or can be defined as global to persist the values for all calls to the service. If a Custom Service Variable has not been assigned a value prior to its use within the service flow or its assignment within the service flow is not valid, the DefaultValue attribute value will be used.
The CustomServiceVariables section must be placed inside the Service node under the Version element.
The name attribute must be unique within the list of variables, and it must begin with the “@” character. The name attribute can be up to a maximum of 100 characters.
The DefaultValue attribute value is mandatory. The value specified will be used to validate against the property values where the variable has been used.