EXTERNAL¶

The ASN.1 EXTERNAL type is a constructed universal type used to encapsulate data that may be defined outside the current ASN.1 module. It typically contains an identifier describing the external data, an optional indirect reference, and the encoded data itself.

In the ASN.1 specification, EXTERNAL is defined as a SEQUENCE with a predefined structure, but in code generation it is represented as a custom type name that inherits the same behavior as any generated SEQUENCE class.

Example ASN.1 definition:

MyExternalData ::= EXTERNAL

which generates a Python class roughly equivalent to:

class MyExternalData(_Asn1BasicType[EXTERNAL]):
    pass

Conceptual Representation¶

class EXTERNAL¶

Inherits from _Asn1Type.

Represents a constructed ASN.1 type where fields are assigned in a fixed order. In the case of EXTERNAL, the generated class will have members as specified by the ASN.1 standard for the EXTERNAL type, such as:

property direct_reference: str | None¶

property indirect_reference: int | None¶

property data_value_descriptor: str | None¶

property encoding: encoding_TYPE¶

Note

Since EXTERNAL is implemented as a specialized SEQUENCE, it will behave identically to any generated SEQUENCE object in Python. This means:

All values are initialized to None if optional.
Non-optional members have default values where applicable.
The object may be directly encodable even without explicitly setting values, depending on the default assignments.

__init__(self, /, **members: Any) → None: Initializes the EXTERNAL instance with optional member assignments. Unspecified optional fields will default to None.

class encoding_TYPE¶

Representation of the encoding field as a CHOICE.

property single_ASN1_type: bytes | None¶

property octet_aligned: bytes | None¶

property arbitrary: bitarray.bitarray | None¶