13.2 Predefined length instances

A number of length instances are already predefined, which only differ in there values for type and unit. They are summarized in the following table

name	type	unit	name	type	unit
`m`	user	m	`v_m`	visual	m
`cm`	user	cm	`v_cm`	visual	cm
`mm`	user	mm	`v_mm`	visual	mm
`inch`	user	inch	`v_inch`	visual	inch
`pt`	user	points	`v_pt`	visual	points
`t_m`	true	m	`w_m`	width	m
`t_cm`	true	cm	`w_cm`	width	cm
`t_mm`	true	mm	`w_mm`	width	mm
`t_inch`	true	inch	`w_inch`	width	inch
`t_pt`	true	points	`w_pt`	width	points
`u_m`	user	m	`x_m`	TEX	m
`u_cm`	user	cm	`x_cm`	TEX	cm
`u_mm`	user	mm	`x_mm`	TEX	mm
`u_inch`	user	inch	`x_inch`	TEX	inch
`u_pt`	user	points	`x_pt`	TEX	points

Thus, in order to specify, e.g., a length of 5 width points, just use 5*unit.w_pt.