How Windows NT Generates MS-DOS Compatible Filenames (99589)
The information in this article applies to:
- Microsoft Windows NT Server 3.1
- Microsoft Windows NT Workstation 3.1
This article was previously published under Q99589 SUMMARY
Windows NT file system (NTFS) filenames do not have the same
limitations that MS-DOS FAT style filenames have. MS-DOS style
filenames are limited to eight and three character strings separated
by a period. NTFS filenames can be much longer and may contain more
types of characters. When Windows NT copies a file from an NTFS
partition to a FAT partition, it needs to change the filename for
compatibility. The following rules are applied when filenames are
converted from NTFS to FAT:
- All spaces in the NTFS filename are removed.
- All periods except the last one preceding a character are removed.
- The first three characters following the last period are used for
the three letter extension of the FAT filename.
- All characters that are illegal in FAT but legal in NTFS are
replaced with underscore characters ("_").
- The first six characters of the NTFS filename, a tilde character
(~), and a single digit are used for the eight letter prefix of
the FAT filename.
If this does not result in a unique filename, only the first five
characters of the NTFS filename are used, followed by the tilde and
two digits.
When filenames are moved from a FAT partition to an NTFS partition, no
conversion takes place because NTFS fully supports the FAT file naming
convention.
| Modification Type: | Major | Last Reviewed: | 10/30/2003 |
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| Keywords: | kbother KB99589 |
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