The named System.Web.Services.Description.MessagePart instances must adhere to the following rules:

• The order of the named System.Web.Services.Description.MessagePart instances reflects the order of the parameters in the RPC (remote procedure call) signature, which is the name of the operation, its input and output parameters, the results it returns and the exceptions it might be asked to handle.

• The return value is not present in the list.

• If the System.Web.Services.Description.MessagePart name appears in both the input and output messages, it is an in/out parameter.

• If the System.Web.Services.Description.MessagePart name appears only in the input message, it is an in parameter.

• If the System.Web.Services.Description.MessagePart name appears only in the output message, it is an out parameter.

Note that this parameter list is not required, even if the System.Web.Services.Description.Operation is to be used with an RPC-style System.Web.Services.Description.Binding. Do not call Operation.ParameterOrderString directly. This method is only used internally for XML serialization. To return the parameter list use Operation.ParameterOrder.