The Free On-line Dictionary of Computing (30 December 2018):

Abstract Syntax Notation 1
ASN.1
X.208

    (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 PDUs 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)