This question is on my mind too. My clients documentations are usually a mix of MS Word & Visio. Lots of repetition and gunk in between.

Ideally, I'd love to find a mechanism that:

  - provides the OO principles in documents; Encapsulations, Abstraction, Polymorphism, Inheritance .
  - Accessible & maintainable by non-techies.
  - Allows scripting (I toyed with PlantUML, but it was a bit rigid).