2.5.9 Task Fields Parameterization
Some of the fields in the XML task definition MAY be parameterized, allowing their values to be substituted with referenced parameter values at task runtime. The server performs parameter substitution if a parameterized field is specified in the format specified in section 2.5.9.1. The potential parameter names are specified in section 2.5.9.2. The XML task definition fields that are parameterized are specified in section 2.5.9.3.