DOS file names

On a disk, every independent collection of instructions or data is a "file." Programs, databases, word procesing documents, spreadsheets and graphics images are examples of files. All files have a name, and almost all files use an extension attached to the name with a period (no spaces in between) that serves as a file type.

The name can be from one to eight characters in length, and the extension can be from one to three. All executable programs in DOS use a .COM or .EXE extension. DOS batch files use a .BAT extension. Executable programs in Windows have an .EXE or .DLL extension. Valid characters are A-Z, a-z, 0-9, ! @ # $ % & ( ) ' ` - { } and ~. Look up extension for a comprehensive list.

DOS file names and Windows 3.x file names are structurally the same. Although, Windows 95/98 supports longer file names, names are often kept to the 8-3 convention for compatibility among all versions. For example, the following files make up the Windows version of this software:

      Name.Extension   Purpose
      CDE.EXE          Software
      CDE.HLP          Help file
      CDE.INI          User preferences

      CDE.ABC          Main index + configuration
      CDE.NDX          Entry index
      CDE.PAR          Paragraph index
      CDE.TXT          Text

The Dot is Sacred
If an extension is used, it is added to the file name with a period, for example, CDE.INI.
As a result, the dot cannot be used in a file name. For example, CD.E.INI isn't valid in DOS. However, if you run a DOS session under Windows 95/98, then multiple dots can be used.

Note!
Directories are named just like files with a name and optional extension.