SUBST--Example

The following command creates a virtual drive Z for the path
B:\USER\BETTY\FORMS:

    subst z: b:\user\betty\forms

Now, instead of typing the full path, you can reach this directory by typing
the letter of the virtual drive, followed by a colon, as in the following
example:

    z:

This example works only if you have included the line LASTDRIVE=Z in your
CONFIG.SYS file to define Z as the highest letter that MS-DOS recognizes as
a disk drive. For more information, see the <LASTDRIVE> command.