2.2.6 Encoding Host Parameters in Host Method Calls
The parameters of a host method call are encoded as follows:
A list of parameters is constructed.
Each element of the list is encoded using the rules described specified in 2.2.6.1. This depends on the type of the parameter.
The list is then converted into UTF-8 encoded XML, equivalent to the XML created by serializing an object with extended properties (see section 2.2.5.2.9).