Antlets are designed to be (optionally) downloaded and imported by the importantlet task sample code

Sample

<?xml version="1.0"?>
<project default="dist" basedir="." name="hello-world">
        <description>Helloworld template project.</description>
    <typedef resource="org/apache/ant/antlet/antlib.xml"     />
    <importantlet name="init" href="http://ant.apache.org/antlets" />
    <target name="dist" >
      <echo message="Build dir is defined in init as ${build.dir}"/>
     </target>
</project>

This will download and automatically import http://ant.apache.org/antlets/init/xbuild.xml Which looks like

<?xml version="1.0"?>
<project  basedir="." name="init.antlet">
        <description>Standard Init.</description>
   <property name="build.dir" value="${basedir}/build}" />
   <mkdir dir="${build.dir}"/>


</project>

Proposals/Antlet/Sample

Sample