# Glossary#

## 1.  Length Units#

The following length units are supported by the reStructuredText parser:

• em (em unit, the element’s font size)

• ex (ex unit, x-height of the element’s font)

• mm (millimeters; 1 mm = 1/1000 m)

• cm (centimeters; 1 cm = 10 mm)

• in (inches; 1 in = 2.54 cm = 96 px)

• px (pixels, 1 px = 1/96 in)

• pt (points; 1 pt = 1/72 in)

• pc (picas; 1 pc = 1/6 in = 12 pt)

This set corresponds to the length units in CSS2 (a subset of length units in CSS3).

The following are all valid length values: “1.5em”, “20 mm”, “.5in”.

Length values without unit are completed with a writer-dependent default (e.g. “px” with HTML, “pt” with latex2e).

## 2.  Percentage Units#

Percentage values have a percent sign (“%”) as unit. Percentage values are relative to other values, depending on the context in which they occur.