Just to give you a feel for something: I have this list of narrative elements which, some time ago, I thought was complete. In the last 2 months I have had to struggle with new ideas until succumbing to the necessity of adding one, and then another, new elements. The dependency '-|' and the isPartOf '.' both are forced on me because they modify the ledger in unique ways not available to other narrative elements.
So then I am tootling along and come to examples of 'isKindOf' that seem compelling ("Peanuts are a kind of legume") which are not affecting any ledger or Thesaurus involving the 'peanut' topic. So what do they mean? I was being forced to add yet one more narrative element and it made me unhappy. Is it possible I was on a slippery slope, where over time one after another new narrative element would appear - making the subject forever incomplete?
Then it dawned on me that we already have the topic of temp_collection. In introducing it, I comment that it still lacks means for reviewing elements or testing element-hood. Well.... 'isKindOf' provides one such testing method, without a review method. In fact, its use does modify a ledger, but it is a ledger built with a Thesaurus of temp_collection related topics. Not typically the same as a ledger about 'peanuts'.
In any case, since it is already a kind of 'topic', the 'isKindOf' does not need representation as an "element". Phew! Dodged a bullet. This last six months or so, working on The Moving Topic, has given me one puzzle after another. The meaning of 'causality' was a puzzle, the difference between 'dependency' and 'deficiency', and now the rescuing of 'isKindOf'. Each of these puzzles has begun as a test and ended as a solidification of the structure. It is reassuringly robust and I had a good day going up one more step.