language, standard, protocol
(ASN.1, X.208, X.680) An ISO
for transmitting structured data
, originally defined in 1984 as part of CCITT X.409 '84. ASN.1 moved to its own standard, X.208, in 1988 due to wide applicability. The substantially revised 1995 version is covered by the X.680 series.
ASN.1 defines the abstract syntax
but does not restrict the way the information is encoded. Various ASN.1 encoding rules provide the transfer syntax
representation) of the data values whose abstract syntax
is described in ASN.1. The standard ASN.1 encoding rules include BER
(Basic Encoding Rules - X.209), CER
(Canonical Encoding Rules), DER
(Distinguished Encoding Rules) and PER
(Packed Encoding Rules).
ASN.1 together with specific ASN.1 encoding rules facilitates the exchange of structured data especially between application programs
over networks by describing data structures in a way that is independent of machine architecture and implementation language. OSI Application layer protocols
such as X.400 MHS electronic mail
directory services and SNMP
use ASN.1 to describe the PDU
s they exchange.
Documents describing the ASN.1 notations: ITU-T
Rec. X.680, ISO
Rec. X.681, ISO
Rec. X.682, ISO
Rec. X.683, ISO
Documents describing the ASN.1 encoding rules: ITU-T
Rec. X.690, ISO
Rec. X.691, ISO
[M. Sample et al, "Implementing Efficient Encoders and Decoders for Network Data Representations", IEEE Infocom 93 Proc, v.3, pp. 1143-1153, Mar 1993. Available from Logica, UK].
See also snacc