> Then we have the same problem with another Node using this Foo node > two times in a row, depending on how it's used by the query parsing > and transform:
hmm, it's hard to imagine such a case being real-world and useful for query jumbling purposes. Also, I think if we introduce something like JUMBLE_NULL() or JUMBLE_POSITION(), the author of a custom jumbling function should use it. This could be added in code comments somewhere, IMO. -- Sami