Variable Names [substvars-name]
===============================

Variable names may only consist of uppercase and lowercase Latin letters,
digits, and hyphens.  Names must be at least one character long.  (A regular
expression for this is `[A-Za-z0-9-]+`.)


Variable Substitutions [substvars-exp]
======================================

Variable substitutions are performed on certain binary control field values, as
explained in $[sectlink][fields-bin].

The format for variable substitutions is as follows:

    ${<var-name>}

`<var-name>` is the name of the variable.