MZMcBride &lt;z(a)mzmcbride.com&gt; writes: Since discussing this on-list last week, someone pointed me to bug #2700 where Roan speculates a year ago about the possible cause of this sort of bug: What I think happens is <tags> get armored before PST; <nowiki> needs this treatment, but for other tags it causes this bug. (See https://bugzilla.wikimedia.org/2700#c48) If Roan is right, then this sort of thing has to be worked around all the time. In fact, if you look at the the most recent comment on #2700 (made tonight), you'll see the troubles of an extension author: https://bugzilla.wikimedia.org/2700#c56 Another comment tonight (this one quite lengthy) on another bug tonight shows that this sort of problem isn't quite zero. https://bugzilla.wikimedia.org/22555#c11 I like the idea of gathering these failures together. Perhaps if they were grouped then we could see the sort of things that experienced wikitext writers just don't do, because they are familiar with the problems. Look at the number of duplicates that #2700 has, the most recent from this past April. And then there is the number of possible duplicates that I'll speculate haven't been filed because people were told “Oh, you can't do that” by someone more experienced than them. Which reminds me: now I am going to work on that report of duplicates that you suggested a few months ago now Mark.