Explicit parameter values, either named or unnamed, can be any type valid in JSON:
Note: Property names that include XML namespaces must be enclosed in double quote marks to ensure that the colon for the namespace is clear.
See the http://www.json.org/json.org site for a good introduction to JSON types and syntax.
Parameter values can also be resolved by the MashZone NextGen Server from a MashZone NextGen attribute. The value passed in the request is a mapping expression that identifies the MashZone NextGen attribute to use to resolve this input parameter.