In trying to do some work with a customization, it struck me that it would be very useful to have a section.class parameter entity, just for the recursive Section element, like: <!ENTITY % local.section.class > <!ENTITY % section.class section %local.section.class; > There's a precedent in that we've already got a refentry.class that fits roughly in the same place in the hierarchy. Having section.class would make it that much easier for users to add Section-like elements in a customization layer, which will have the added benefit of helping to dispel the notion that DocBook can't be extended by adding new sub-Book/Article/Chapter sectioning elements. This relates to the discussion about Topic, providing something more suitable for online help, etc.-- and the issue of people not grokking that they can use sub-Book/Article/Chapter elements (e.g. Section or equivalent) as root elements in doc instances.