• Indexterms should not be embedded directly into a question or answer element but into a deeper paragraph, optimally right after the referenced word without spaces even [1] but somehow the schema allows badly nested indexterms. Correct such entires in the whole documentation set.
• Add constraints to check for invalid indexterm entries.

See also: http://www.sagehill.net/docbookxsl/GenerateIndex.html#Indexterms [1]