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In computing, a code page is a table of values that describes the character set used for encoding a particular set of glyphs, usually combined with a number of control characters. The term "code page" originated from IBM's EBCDIC-based mainframe systems,〔(IBM i Globalization - EBCDIC Code Pages )〕 but many vendors use this term including Microsoft, SAP,〔(【引用サイトリンク】title=Code Page )〕 and Oracle Corporation.〔(【引用サイトリンク】title=Glossary )〕 Vendors often allocate their own code page number to a character encoding, even if it is better known by another name (for example UTF-8 character encoding has code page numbers 1208 at IBM, 65001 at Microsoft, 4110 at SAP). == The code page numbering system == IBM introduced the concept of systematically assigning a small, but globally unique, 16 bit number to each character encoding that a computer system or collection of computer systems might encounter. The IBM origin of the numbering scheme is reflected in the fact that the smallest (first) numbers are assigned to variations of IBM's EBCDIC encoding and slightly larger numbers refer to variations of IBM's extended ASCII encoding as used in its PC hardware. With the release of PC DOS version 3.3 (and the near identical MS-DOS 3.3) IBM introduced the code page numbering system to regular PC users, as the code page numbers (and the phrase "code page") were used in new commands to allow the character encoding used by all parts of the OS to be set in a systematic way.〔The MS-DOS Encyclopaedia, Microsoft press (1988, ISBN 1-55615-049-0, ISBN 978-1-55615-049-4)〕 After IBM and Microsoft ceased to cooperate in the 1990s, the two companies have maintained the list of assigned code page numbers independently from each other, resulting in some conflicting assignments. At least one third-party vendor (Oracle) also has its own different list of numeric assignments.〔 IBM's current assignments are listed in their CCSID repository, while Microsoft's assignments are documented within the MSDN.〔(【引用サイトリンク】title=Code Page Identifiers )〕 Additionally, a list of the names and approximate IANA abbreviations for the installed code pages on any given Windows machine can be found in the Registry on that machine (this information is used by Microsoft programs such as Internet Explorer). Most well-known code pages, excluding those for the CJK languages and Vietnamese, fit all their code-points into eight bits and do not involve anything more than mapping each code-point to a single character; furthermore, techniques such as combining characters, complex scripts, etc., are not involved. The text mode of standard (VGA-compatible) PC graphics hardware is built around using an 8-bit code page, though it is possible to use two at once with some color depth sacrifice, and up to eight may be stored in the display adaptor for easy switching.〔(【引用サイトリンク】title=VGA/SVGA Video Programming--VGA Text Mode Operation )〕 There was a selection of third-party code page fonts that could be loaded into such hardware. However, it is now commonplace for operating system vendors to provide their own character encoding and rendering systems that run in a graphics mode and bypass this hardware limitation entirely. However the system of referring to character encodings by a code page number remains applicable, as an efficient alternative to string identifiers such as those specified by the IETF and IANA for use in various protocols such as e-mail and web pages. 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「Code page」の詳細全文を読む スポンサード リンク
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