![]() ![]() Other implementationsīefore LFN support was implemented into the FAT family of file systems, various file managers provided their own methods to attach and maintain longer file descriptions. ![]() Although drivers such as DOSLFN can be loaded in almost any versions of DOS, it works best on DOS versions that have support for LFN themselves, such as MS-DOS 7.10, so that DOS commands such as DIR would show long file names as well. The following is a list of drivers that can be used to provide support for VFAT long file names as used in Windows 95. 255-character mixed-case long filename is possible only for files or folders with no sub-folders at the root folder of any drive. The maximum length of a pathname is 256 characters, which includes all parent directories and the filename. This is achieved by chaining up to 20 directory entries of 13 2-byte Unicode characters each. The long filename system allows a maximum length of 255 UCS-2 characters including spaces and non-alphanumeric characters (excluding the following characters, which have special meaning within the COMMAND.COM command interpreter or the operating system kernel: / : * ? " |). This problem does not exist for FAT32 volumes. There is space only for 25 long filenames of maximum length (512/20). Since long filenames use more than one directory entry, this problem may occur with fewer than 512 files or folders in the root directory. Also, one is more likely to encounter issues creating files or folders in the root directory, since FAT12 and FAT16 only allocate space for 512 root directory entries on hard disks. ![]() Limitsīecause the FAT LFN implementation is layered atop an older, more limited naming system, there are inevitable complications, such as if an attempt is made to create too many files with the same first six letters. Many APIs providing access to files by pathname cannot see the new, longer names without a supporting driver. LONGNAME extended attributes that are incompatible with Microsoft's implementation and only visible to tools supporting OS/2's standard. However, the Windows 95 version of File Manager came from Windows for Workgroups 3.11. NT 3.5 added FAT LFN support in preparation for Windows 95. Windows NT supported LFNs on NTFS file systems starting with the release of NT 3.1, and all of its utilities, including File Manager, were updated to support LFNs. Microsoft did not add LFN support to many of its older programs, including File Manager, the Windows 3.1x (Windows for Workgroups) file manager that was made obsolete by the new operating system shell, Windows Explorer. Upon booting into plain DOS, the long filenames are not visible unless a VFAT LFN driver is installed. 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. 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. Programs running on older OSs could still access the files' short names, while newer, LFN-aware OSs and programs could use the longer ones. 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 was chosen for compatibility, as volume labels are generally ignored by programs and operating system (OS) components.
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