OER encode/decode functions are generated when the -oer switch or the - coer switch is specified on the command line. For each ASN.1 production defined in the ASN.1 source file, a C OER decode function is generated. This function will parse the data contents from an OER-encoded ASN.1 message and populate a variable of the corresponding type with the data. If the - coer switch is specified, then the encode and decode operations will be done using the x696 (ITU-T X.696 / ISO/IEC 8825-7:2014) canonical rules.

If C++ code generation is specified, a control class is generated that contains a Decode 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.