5.20.1 Changing the Type Size

Request: .ps [size]
Request: .ps +size
Request: .ps -size
Escape sequence: \ssize
Register: \n[.s]

Use the ps request or the \s escape sequence to change (increase, decrease) the type size (in scaled points). Specify size as either an absolute type size, or as a relative change from the current size. ps with no argument restores the previous size. The ps request’s default scaling unit is ‘z’. If the requested size is non-positive, it is set to 1u.

The read-only string-valued register .s interpolates the type size in points as a decimal fraction; it is associated with the environment (see Environments). To obtain the type size in scaled points, interpolate the .ps register instead (see Using Fractional Type Sizes).

snap, snap,
.ps +2
grin, grin,
.ps +2
wink, wink, \s+2nudge, nudge,\s+8 say no more!
.ps 10

The \s escape sequence supports a variety of syntax forms.

\sn

Set the type size to n points. n must be a single digit. If n is 0, restore the previous size.

\s+n
\s-n

Increase or decrease the type size by n points. n must be exactly one digit.

\s(nn

Set the type size to nn points. nn must be exactly two digits.

\s+(nn
\s-(nn
\s(+nn
\s(-nn

Increase or decrease the type size by nn points. nn must be exactly two digits.

See Using Fractional Type Sizes, for further syntactical forms of the \s escape sequence that additionally accept decimal fractions.

The \s escape sequence affects the environment immediately and doesn’t produce an input token. Consequently, it can be used in requests like mc, which expects a single character as an argument, to change the type size on the fly.

.mc \s[20]x\s[0]
Request: .sizes s1 s2 … sn [0]

Some devices may permit only certain type sizes, in which case GNU troff rounds to the nearest permissible size. The DESC file normally specifies which type sizes are allowed by the device.

Use the sizes request to change the permissible sizes for the output device. Arguments are in scaled points; See Using Fractional Type Sizes. Each can be a single type size (such as ‘12000’), or a range of sizes (such as ‘4000-72000’). You can optionally end the list with a zero.