No.

To quote
http://phd.netcomp.monash.edu.au/RobertMarkBram/notes/ant/tutorial/default.asp:

 "Ant build files must be well formed XML documents. However, there
 are no formal DTD's or XML Schemas for Ant build files. Ant doesn't
 have DTD's or XML Schemas essentially because the rules for a valid
 Ant build file can change so easily. For example, Ant allows you to
 create your own types of XML elements and use them in your build
 files - which would immediately make your build file invalid
 according to the 'standard' DTD or XML Schema."

So the reason is that ant is a collection of custom rules, with ant
tasks (new tags) "plugged in" as needed. It would be hell if every
task was another namespace, which would be the consequence of
requiring a schema or DTD.

ionFreeman@gmail.com (Ion Chalmers Freeman) wrote on 1 Oct 2004
17:18:34 -0700 in comp.lang.java.programmer:

You can generate a DTD for a build.xml file with the antstructure
task:

 <target name="dtd">
     <antstructure output="project.dtd"/>
 </target>