luametatex-tex.tex defines and shortly thereafter uses a Lua function document.showprimitives. The definition of the function uses: table.sortedpairs(tex.extraprimitives(tag)) tex.extraprimitives(tag) returns a sequence. table.sortedpairs sorts on the keys of the sequence. In the case of a sequence, table.sortedpairs is equivalent to ipairs, and probably not what is intended here. See the results of the current uses of document.showprimitives in the PDF. They are not sorted alphabetically. There probably should be a sort on the values of the sequence returned by tex.extraprimitives(tag). A few weeks ago, this problem was present in the LuaTeX manual, too.