For each ASN.1 production defined in the ASN.1 source file, a decode method may be generated. This method will decode an ASN.1 message into public member variables within the C# object.

As was the case for encode methods, a decode method is only generated if it is required to alter the behavior of the base class. The C# model is built on inheritance from a set of common run-time base classes. MDER supports only a few primitive types, and most of these are subsets of ASN.1 built-in types. Therefore, in most cases, there is not an applicable MDER decode method in the common run-time base class and so a decode method will be generated.