Epson Apex 20020 - Manual (Page 81)

If you press Enter when a command line has an error in it, the
screen displays an error message. Usually, the command prompt
reappears so you can try again. Type the correct command and
press Enter.
Creating and Managing Files
All your data and programs are stored in files on disk. A data
file contains information, such as words, numbers, or pictures.
A program file contains instructions that the computer can
understand and execute.
The kind of file you create depends on the MS-DOS command
or application program you use to create it. In general, a data
file that you create using an application program is stored in a
special format. If you use a different application program to
read that file, you may encounter problems.
When you create a file, you need to give it a name. You must
name your files in a certain format required by MS-DOS.
Naming Files
Each file must have a unique filename so you can retrieve it
when you need to. The filename consists of two parts: the name
and the extension (which is optional).
You can choose a name up to eight characters long. Create a
name that identifies the information the file contains. The
name can contain any characters or numbers except for blank
spaces and the following symbols:
Using MS-DOS With Your Computer 4-9