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 source and binary control field
values, as explained in $[sectlink][fields].

The format for variable substitutions is as follows:

    ${<var-name>}

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


Special Variables [substvars-defined]
=====================================

The following substitution variables shall be set:

  * `Source-Version`

    The source package version, as given in the most recent entry of the change
    log.  See $[sectlink][src-ver] for the syntax of source package version
    identifiers.

  * `Binary-Version`

    The binary package version, as given in the most recent entry of the change
    log.  See $[sectlink][src-ver] for the syntax of source package version
    identifiers.

  * `Host-Arch`

    The distribution architecture string of the host system.

  * `Host-Plat`

    The application platform of the host system.


Defining Substitution Variables [substvars-custom]
==================================================

Substitution variables may be defined in a file called `substvars`.  See
$[sectlink][control] for the format of this file.

Names must conform to the requirements outlined in $[sectlink][substvars-name].
Values may be comprised of multiple lines, and empty lines at the beginning and
end of each substitution variable value shall be removed.