Epson Apex 20020 - Manual (Page 80)

FORMAT is the command name to execute the file
FORMAT.COM. The A: is a parameter that tells the
command what to format-in this case, the diskette in drive A.
The space between FORMAT and A: is the delimiter that lets
MS-DOS distinguish the command name (FORMAT) from
the parameter (A:).
Some commands also have optional switches you can use. A
switch is a type of parameter that alters the effect of a
command. For example, suppose you want to make a copy of a
single-sided diskette. To do this, you need to add a switch to
the DISKCOPY command like this:
DISKCOPY A: A:/1
Without the /1 switch, DISKCOPY would expect the diskette
to be double-sided. Switches are preceded by a forward slash: 1.
See your MS-DOS Reference Manual for more information on
the command format. Also see your MS-DOS manual for
command descriptions that tell you which parameters and
delimiters are required for each command and which optional
parameters and switches you can use.
You can enter an MS-DOS command whenever you see the
MS-DOS command prompt. Type the command name and any
necessary parameters and delimiters and then press
Enter to
execute the command. MS-DOS does not execute your
command until you press
Enter.
You can type command names and parameters in either
uppercase or lowercase letters. If you make a mistake when
typing a command and you notice it before you press Enter,
you can do either of two things:
Use the backspace key to back up to the error so you can
correct it
Press
E
SC
to cancel the command line.