DocBook is an XML standard maintained by OASIS. Like DITA, DocBook is designed for technical communicators. It is used extensively in the computer industry and open-source software community. DocBook can be an excellent choice for creating content for Flare, and if you need to migrate content from DocBook into Flare, you should be able to do so easily.
You can not import DocBook content directly into Flare. However, DocBook has a set of open-source style sheets that generate HTML that can be readily imported into Flare. Here are a few of the reasons why DocBook works well with Flare: