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Abstract Syntax Notation One (ASN.1) is a standard and notation that describes rules and structures for representing, encoding, transmitting, and decoding data in telecommunications and computer networking. The formal rules enable representation of objects that are independent of machine-specific encoding techniques. Formal notation makes it possible to automate the task of validating whether a specific instance of data representation abides by the specifications. In other words, software tools can be used for the validation.〔(Using ASN.1 ) (Abstract Syntax Notation 1): A Data Description Language〕 ASN.1 is a joint standard of the International Organization for Standardization (ISO), International Electrotechnical Commission (IEC), and International Telecommunication Union Telecommunication Standardization Sector ITU-T, 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. The latest available version is dated 2008, and is backward compatible with the 1995 version. ==ASN.1 in transfer== Data generated at various sources of observation may need to be transmitted to other locations before it can be processed. For example, a radio telescope in outer space might produce voluminous signal data that it cannot process locally. The system recording the data and the system processing it later may be very different in nature, and may even be produced by different vendors. A consistent mechanism is needed to record, transmit, and read data across diverse systems. 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: *Basic Encoding Rules (BER) *Canonical Encoding Rules (CER) *Distinguished Encoding Rules (DER) *XML Encoding Rules (XER) *Canonical XML Encoding Rules (CXER) *Extended XML Encoding Rules (E-XER) *Packed Encoding Rules (PER, unaligned: UPER, canonical: CPER) *Generic String Encoding Rules (GSER) 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 and Lightweight Directory Access Protocol (LDAP) directory services, H.323 (VoIP), Kerberos, BACnet and simple network management protocol (SNMP) use ASN.1 to describe the protocol data units (PDU) they exchange. It is also extensively used in the access and non-access strata of the Universal Mobile Telecommunications System (UMTS). There are many other application domains of ASN.1.〔(ITU-T website - Uses of ASN.1 )〕 A particularly useful new application of ASN.1 is Fast Infoset. Fast Infoset is an international standard that specifies a binary encoding format for the XML Information Set (''XML Infoset'') as an alternative to the XML document format. It aims to provide more efficient serialization than the text-based XML format. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Abstract Syntax Notation One」の詳細全文を読む スポンサード リンク
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