Yesterday we run into another Saxon bug. See NPE in CaseVariants.
The problem happened just once and never reproduced. Inspection of Saxon sources hinted that it can be a race condition.
Michael Kay agreed with our conclusion and fixed the problem in the code along with several other similar places.
It is such rare kind of bug that it might appear once during whole product life cycle. So, we may consider the fix is personal.
a@href@title, b, blockquote@cite, em, i, strike, strong, sub, super, u