Epson 8900 Series - Manual (Page 150)

IBM Proprinter XL Emulation 7-20
Enable/Disable Double-High Double-Wide Print
Escape sequence: ESC [ @ n1 n2 n3 n4 m1 m2
Hexadecimal: 1B 5B 40 n1 n2 n3 n4 m1 m2
where:
n1 n2 = byte count; format is (n1 + (n2 * 256))
n3 n4 = no function, ignored
m1 = line spacing and character height
m2 = character width
This command selects double-high printing in either the standard or
expanded width. The variable m2 specifies the character width, and
m1 specifies the character height and line feed distance as follows.
Considerations for Using Enable/Diasble Double-High
Double-Wide Print
Considerations for using the Enable/Disable Double-High
Double-Wide command sequence are:
q The byte count is usually four (4), when the count is greater than
4, the command is executed as per m1 and m2 and the additional
bytes are accepted and ignored.
q When the byte count is three (3), the command is executed as per
m1 only.
No m2 byte is provided, the character width remains unchanged.
m1 is the last byte of the count.
q When the byte count is less than three (3) the command is
accepted and ignored as follows:
byte count = 2 n4 is the last byte of the sequence
1 n3 is the last byte of the sequence
0 n2 is the last byte of the sequence