For each ASN.1 production defined in the ASN.1 source file, a C XML decode function is generated. This function will parse the data contents from an XML message of the corresponding ASN.1 or XML schema type and populate a variable of the C type with the data.

If C++ code generation is specified, a control class is generated that contains a DecodeFrom method that wraps this function. This function is invoked through the class interface to encode an ASN.1 message into the variable referenced in the msgData component of the class.