Epson Apex 20020 - Manual (Page 79)

For example, if you have two diskette drives, and are logged
onto drive A, you could format a diskette in drive B with the
command:
FORMAT B:
In this case, MS-DOS looks on drive A, the default drive, for
the file named FORMAT.COM. If the diskette in that drive
contains the file FORMAT.COM (as does the Startup
diskette), MS-DOS finds it there. If you are logged onto drive
B, however, you would need to enter the command like this:
A:FORMAT B:
This tells MS-DOS to look on drive A for FORMAT.COM.
Entering an MS-DOS Command
To enter an MS-DOS command, you need to type the
command in the correct format. The command format provides
MS-DOS with the information needed to perform a task.
The MS-DOS command format consists of the command
name, parameters, and delimiters. The command name tells
MS-DOS the task you want the computer to perform.
Parameters specify details such as what data you want to
process and where to locate or store a file. Delimiters are
characters such as spaces or commas that separate command
names and parameters.
For example, the command to format a diskette in drive A is:
Using MS-DOS With Your Computer 4-7