The generation of methods to encode data in accordance with the Octet Encoding Rules (OER) is similar to how methods were generated in the BER/DER case discussed previously. For each ASN.1 production defined in the ASN.1 source file, a C# encode method may be generated. This function will convert a populated variable of the given type into an encoded ASN.1 message.

An encode method is only generated if it is required to alter the encoding of the base class method. The C# model is built on inheritance from a set of common run-time base classes. These run-time classes contain default implementations of encode/decode methods that handle the encoding/decoding of the basic types.

For simple assignments, the generation of an encode method is not necessary. For example, the following production will not result in the generation of an encode method:

   X ::= INTEGER

In this case, the generated C# class extends the Asn1Integer base class and the default encode method within this class is sufficient to encode a value of the generated type.

An encode method is typically only generated when a testable constraint is present.

For example, the following declaration will cause a custom encode method to be generated because the value range constraint is OER-visible and alters the encoding:

   X ::= INTEGER (1..255)

In this case, special logic is necessary to apply the value range constraint.

Constructed types (SEQUENCE, SET, SEQUENCE/SET OF, and CHOICE) will always have a generated encode method.