All told, the plugin includes about 100 quality checks, which you can customize to your needs. You will need to write xpath expressions—for which there are several online resources. Running a map through the plugin generates a report in HTML, which summarizes the errors by type, then lists them per-file. (To customize the checks, simply edit qachecks.xsl).
The plugin is great for daily quality assurance tasks, but you can also use it to prepare for a transition to a set of DITA constraints. Let’s say you began your implementation pre-DITA 1.2 and have a bunch of “legacy” data. Now you want to adopt 1.2 and have devised a set of constraints. You can describe element structures, via xpath within the plugin, that do not comply with your new constraints, then process your documents to see how much work you’ll need to do to get your old document in line with the new constraints. We imagine you could then automate some or all of the conversion based on the results. (Hmm.. that sounds like a new plugin idea…)
We have more posts on the QA plugin planned; in the meantime, if you have any questions, don’t hesitate to post them in the comments section.