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Long filename (LFN) support is Microsoft's backward compatible extension of the 8.3 filename (short filename) naming scheme used in Microsoft DOS. Long filenames can be more descriptive, including longer extensions common on other operating systems such as .jpeg, .tiff, .html, and .xhtml rather than specialized shortened names such as .jpg, .tif, .htm, or .xht. The standard has been common with FAT filesystems since its first implementation in Windows NT 3.5 of 1994.To maintain compatibility with older operating systems, Microsoft formulated a method of generating an 8.3 filename from the long filename (for example, Microsoft.txt to MICROS~1.TXT) and associating it with the file.==Compatibility issues== Microsoft implemented support for LFNs in the FAT filesystem by using hidden directory entries—of the ''volume label'' type—to store the longer names; this scheme is known as VFAT, and it was chosen for compatibility, as volume labels are generally ignored by programs and operating system components. Programs running on older operating systems could still access the files' short names, while newer, LFN-aware operating systems and programs could use the longer ones. When LFN support was first introduced into an MS-DOS-based operating system in the form of Windows 95, it caused some problems for older programs. For example, a DOS program performing sector-level directory operations while Windows was in DOS mode could destroy long filename information so, by default, sector-level access to hard disks was disallowed in this mode. Upon booting into plain DOS, the long filenames are not visible unless a VFAT LFN driver has been installed. Microsoft did not add LFN support to many of its older programs, including File Manager, the Windows for Workgroups file manager that was made obsolete by the new operating system shell, Explorer. Windows NT supported LFNs on NTFS file systems beginning with the release of NT 3.1, and all of its utilities, including File Manager, were updated to support LFNs. NT 3.5 added FAT LFN support in preparation for Windows 95. However, the Windows 95 version of File Manager came from Windows for Workgroups 3.11. OS/2 stores LFNs for FAT filesystems in .LONGNAME extended attributes that are incompatible with Microsoft's implementation and only visible to tools supporting OS/2's standard. Many APIs providing access to files by pathname can not see the new, longer names without a supporting driver.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「long filename」の詳細全文を読む スポンサード リンク
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