This is another problem that goes back to at least 3.2: the examples starting with the Items method display (in the PDF at least) with square, black boxes where the ",," should be. The idea, I believe, is to illustrate a sparse array with the second and fourth items being empty so the fix would be to change the ",," to ", ,". However, I cannot verify that since I have never built the docs. If someone will try this change for Items and confirm that it fixes the problem, I will do a search and replace for all ",," and submit a patch file. BTW, it seems strange that docbook won't allow ",," in its source??