Common Desktop Environment: Help System Author's and Programmer's Guide

Syntax

<keycap>keycap characters<\keycap>

Or:

[[keycap characters]] 

The shorthand form is [[ (two left square brackets) and ]] (two right square brackets) before and after the keycap characters.

Entity references for special symbol characters, such as arrows, can be used. Multiline keycaps are not available.