Ant: the subant tag

In SVN I have this hierarchy:

trunk/ --+
+ subProjectA/ -+
| |
| +- build.xml
+ subProjectB/ -+
+- build.xml

under trunk I've added a build.xml file and using the Ant 1.6 tutorial I've added this build.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<project default="dist" name="My Project">
<macrodef name="iterate">
<attribute name="target"/>
<subant target="@{target}">
<fileset dir="." includes="*/build.xml"/>

<target name="dist">
<iterate target="dist"/>

<target name="compile">
<iterate target="compile"/>

<target name="clean">
<iterate target="clean"/>

This presumes all sub projects have a compile, clean, and dist target. I may add a test target as well.