Lengths

A valid length may have any of the following forms (where # is a floating-point number):

#

The number specifies a distance in pixels.

#c

The number specifies a distance in centimeters on the screen.

#i

The number specifies a distance in inches on the screen.

#m

The number specifies a distance in millimeters on the screen.

#p

The number specifies a distance in printer’s points (1/72 inch) on the screen.

Whitespace is permitted between the number and distance-unit character.