In telecommunications and computer networking Abstract Syntax Notation one (ASN.1) is a standard and flexible notation that describes data structures for representing, encoding, transmitting, and decoding data. It provides a set of formal rules for describing the structure of objects that are independent of machine-specific encoding techniques and is a precise, formal notation that removes ambiguities. BlackBerry 7100t Telecommunication refers to communication over long distances. ... A computer network is a system for communication among two or more computers. ... The word standard has several meanings: Originally, standard referred to a conspicuous object used as a rallying point in battle. ... Data is the plural of datum. ...

ASN.1 is a joint ISO and ITU-T standard, originally defined in 1984 as part of CCITT X.409:1984. 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. ISO has many meanings: Iso is the stem of the Latin transliteration of the Greek word ίσος (ísos, meaning equal). The iso- prefix in English derives from this and means equality or similarity. ... The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication Union (ITU) and is based in Geneva, Switzerland. ... 1984 is a leap year starting on Sunday of the Gregorian calendar. ... 1988 is a leap year starting on a Friday of the Gregorian calendar. ... 1995 was a common year starting on Sunday of the Gregorian calendar. ...

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), CER (Canonical Encoding Rules), DER (Distinguished Encoding Rules), PER (Packed Encoding Rules), and XER (XML Encoding Rules). Abstract syntax is a representation of data (typically either a message passing over a communications link or a computer program being compiled) which is independent of machine-oriented structures and encodings and also of the physical representation of the data (called concrete syntax in the case of compilation or transfer... Basic encoding rules (BER) are ASN.1 encoding rules for producing self-identifying and self-delimiting transfer syntax for data structures described in ASN.1 notations. ... Canonical encoding rules (CER) are a restricted variant of basic encoding rules for producing unequivocal transfer syntax for data structures described by ASN.1. ... DER or Distinguished Encoding Rules is a method for encoding a data object, such as an X.509 certificate, to be digitally signed or to have its signature verified. ... Packed encoding rules (PER) are ASN.1 encoding rules for producing a compact transfer syntax for data structures described in ASN.1, defined in 1994. ... The Extensible Markup Language (XML) is a W3C-recommended general-purpose markup language for creating special-purpose markup languages. ...

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.

Application layer protocols such as X.400 electronic mail, X.500 directory services, H.323 (VoIP) and SNMP use ASN.1 to describe the PDUs they exchange. It is also extensively used in the Access and Non-Access Strata of UMTS. There are many other application domains of ASN.1 [1]. The application layer is the seventh level of the seven-layer OSI model. ... In computing, X.400 is a OSI standard developed by the ITU-T (at the time the CCITT) and promulgated by ISO for the exchange of email (at the time called IPMs - Inter Personal Messages). ... Electronic mail, abbreviated e-mail or email, is a method of composing, sending, and receiving messages over electronic communication systems. ... X.500 is the set of ITU-T computer networking standards covering electronic directory services such as white pages, Knowbot and whois. ... A directory service organizes computerized content and runs on a directory server computer. ... H.323 is an umbrella recommendation from the ITU-T, that defines the protocols to provide audio-visual communication sessions on any packet network. ... IP Telephony, also called Internet telephony, is the technology that makes it possible to have a telephone conversation over the Internet or a dedicated Internet Protocol (IP) network instead of dedicated voice transmission lines. ... The Simple Network Management Protocol (SNMP) forms part of the internet protocol suite as defined by the Internet Engineering Task Force. ... In telecommunications, the term protocol data unit (PDU) has the following meanings: Information that is delivered as a unit among peer entities of a network and that may contain control information, address information, or data. ... Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile phone technologies. ...

Many free and commercial tools for ASN.1 are available [2].

Standards

Standards describing the ASN.1 notation (free download from the ITU-T website):

• ITU-T Rec. X.680 | ISO/IEC 8824-1
• ITU-T Rec. X.681 | ISO/IEC 8824-2
• ITU-T Rec. X.682 | ISO/IEC 8824-3
• ITU-T Rec. X.683 | ISO/IEC 8824-4

Standards describing the ASN.1 encoding rules (free download from the ITU-T website):

• ITU-T Rec. X.690 | ISO/IEC 8825-1 (BER, CER and DER)
• ITU-T Rec. X.691 | ISO/IEC 8825-2 (PER)
• ITU-T Rec. X.693 | ISO/IEC 8825-4 (XER)

List of all ASN.1 standards

See also

• TTCN

TTCN is a programming language dedicated to testing of communication protocols. ...

References

• Federal Standard 1037C
• MIL-STD-188.
• Other references

Federal Standard 1037C entitled Telecommunications: Glossary of Telecommunication Terms is a U.S. Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. ... MIL-STD-188 is a series of U.S. military standards relating to telecommunications. ... The Free On-line Dictionary of Computing (FOLDOC) is an on-line, searchable encyclopedic dictionary of computing subjects. ... GNU logo The GNU Free Documentation License (GNU FDL or simply GFDL) is a copyleft license for free content, designed by the Free Software Foundation (FSF) for the GNU project. ...

External links

• The ASN.1 Consortium
• ASN.1 Information site
• Other links
• ASN.1 tutorial