from
The Free On-line Dictionary of Computing (8 July 2008)
Abstract Syntax Notation 1
ASN.1
X.208
<language, standard, protocol> (ASN.1, X.208, X.680) An
{ISO}/{ITU-T} {standard} for transmitting structured {data} on
{networks}, 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} of {information} but does
not restrict the way the information is encoded. Various
ASN.1 encoding rules provide the {transfer syntax} (a
{concrete} 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}, {X.500} 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} 8824-1; {ITU-T} Rec. X.681, {ISO} 8824-2; {ITU-T}
Rec. X.682, {ISO} 8824-3; {ITU-T} Rec. X.683, {ISO} 8824-4
Documents describing the ASN.1 encoding rules: {ITU-T}
Rec. X.690, {ISO} 8825-1; {ITU-T} Rec. X.691, {ISO} 8825-2.
[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}.
(2005-07-03)