Drupal has all the elements to build a custom content model that can mirror a DITA specialisation. The really exciting thing is that this data model can be built from the UI, without a single line of code. While there are considerable drawbacks to the usability of the resulting interface, the fact that this is a free and open source implementation means that those who have more time than money could use this implementation as a starting point to build a DITA CCMS that accommodates an arbitrary specialisation.