[syslog-ng] How do I get pdbtool to create version 4 patterndb.xml?

All, I'm trying to create patterndb version 4 XML so I can make use of its additional features over version 3. However pdbtool seems only to output version 3 XML. I verified that all of my component XML files are version 4, and used pdbtool from syslog-ng 3.3.5: $ /opt/syslog-ng/bin/pdbtool merge --pdb=/tmp/patterndb.xml --recursive --glob='*.pdb' --directory=/etc/syslog-ng/patterndb.d/ The generated file is version 3: $ head -2 /tmp/patterndb.xml <?xml version='1.0' encoding='UTF-8'?> <patterndb version='3' pub_date='2012-05-07'> How do I generate version 4 XML?