NULL

The ASN.1 NULL type represents the presence of a value without carrying any data. It is most often used in control structures, protocol markers, or to indicate that a certain choice or option is intentionally left empty.

In Python, the generated NULL type acts as a singleton-like type that can be instantiated but always holds the same conceptual meaning: “no value”.

Note

Unlike Python’s built-in None, the ASN.1 NULL type is an actual encoded value on the wire — it is represented by a zero-length payload and an ASN.1 tag.

Example ASN.1 definition:

MyNull ::= NULL

would generate the following Python class:

class MyNull(_Asn1BasicType[None]):
    pass

Conceptual Representation

class _Asn1BasicType[None]

Represents a NULL value. This type ignores any assigned value and always returns None when accessed.

__init__(self) → None

Creates a NULL instance. Since the type has no internal data, no parameters are accepted.

property value: None

Always returns None. Any attempt to set value will overwrite nothing — the result is still None.