The .SPACING command changes the amount of spacing between lines
of text.
Format
.SPACING n
Abreviated format
.SP n
1 – Parameter
n
The amount of spacing that you want between lines of text. For
example, 1 denotes single spacing (no blank lines between lines
of text). You must specify n, which must be within the range of 1
to 5, inclusively.
2 – Default
If you do not enter a .SPACING command, you get single spacing
(.SPACING 1).