The application descriptor file DTD describes the format of the bar-descriptor.xml file.
If you want to look at the full DTD for the bar-descriptor.xml file, download the DTD here (online access required).
The top-level element for the bar-descriptor.xml file is the <qnx> element. In general, there is no order for child elements under the parent elements - except for the <arg> element. The syntax of the elements of the bar-descriptor.xml file is described in the sections that follow.