<?xml version='1.0'?>
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
<para>Note that running programs that access the network or mount/unmount
filesystems is not allowed inside of udev rules, due to the default sandbox
that is enforced on <filename>systemd-udevd.service</filename>.</para>
+ <para>Please also note that <literal>:=</literal> and <literal>=</literal> are clearing
+ both, program and builtin commands.</para>
</listitem>
</varlistentry>