Howdy all!
First, Nautile, please allow me to make a minor course correction here. Brian didn't say
" a knot to put at the end of a ratline"
... He merely pointed out (correctly) that ratlines are a place where Clove Hitches are used. They're actually used in the crossings. The ends are usually eyes whipped to the rigging or some such... ABOK# 1176, 1177, 3437.
But I digress.
It's interesting that Brian chose the Clove Hitch as an example, because that's an example I use too. I hope no one will think I'm criticizing Brian (or anyone else) in any way if I glom on here...
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Opinion ]
The internal working of a Clove Hitch is basically thus: one Turn crosses the SPart, holding it to the spar/tree/shroud, while the Tag end puts Tension on that Crossing to secure ("nip") it. The Tag end and the Tension it provides are held by the second Crossing of the diagonal part that runs between the two Turns.
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/Opinion ]
That's how I see it, anyway. I see a lot of CH's tied as crossing knots (ratlines, pilings, crowd control) (ABOK# 1178, e.g.) as well as the form where both ends pull away from the "something" as ABOK# 400 & 1670. I do those, but the point here is I sometimes do a much different "set" of that same knot, which makes it a more powerful tool for me.
Picture a boat, an island, and a harsh storm blowing in. We beach the boat to set up camp. I haul on the bow line to stick the keel in the sand, as the rest of the crew tumbles out to deploy shelter. Okay, it's 175 pounds pulling 2500 up a beach -- the word "stick" may be optimistic!

But I need to make it fast NOW, before the storm hits, plus I have duties on the tarps.
I haul on the bow line & pass it around a tree (sweetgum, if it matters), holding all the Tension I can & taking the Tag end close under the SPart. Then I lead the Tag end up (I started with "under") and over the SPart where the SPart makes good contact on the tree. The Tag end now holds the SPart against the tree (Friction holding Tension), so I can relax a little. Now I pass the Tag end further around and up the tree, holding a Bight & being careful to not disturb that crossing Bight that holds the SPart. I Tuck the Tag end under that Bight & haul away on it
further around and
further up the tree. The diagonal piece now holds the SPart
and the Tag end, but separated by several inches & 180 degrees + of rotation around the tree. That's all I had time for, as tents needed casting and the usual camping chores needed to be done, all with a major summer thunderstorm bearing down hard on us.
The knot looked a mess, but after the storm passed, with no other rope tricks, we still had the boat. I've used the CH this way a lot of times, with different types of cordage, and (when it comes out of my hands) it works perfectly.
I've never seen this usage mentioned, so the enumeration of usages wouldn't have helped me here. The customary structural view of a CH doesn't consider the splitting of the two Turns nor the nipping points -- not that I've found. The only way I could get there was to haul the SPart tight & nip it with the tag end & then repeat that operation with the top Turn... Okay, I confess, it's harder to read than to describe than to do. Sorry.
The point being, it works, although it requires you pull your second crossing way around. (changing structure) It also requires a very rough (and round) hitchee. And no, it probably won't work that way for anyone else.
Now...
You know the Clove Hitch. You know where Clove Hitches have been used historically. Can you see my knot? Is that the knot you'd choose to use, given the same scenario?
Perhaps, but I maintain that the "Internal Workings" view is the only way I was able to adapt that knot to that problem. And yes, (PABPRES) I know the correct answer was to use the right knot!!

I just didn't have anything else "in my hands" at that time.

Anyway, enough about me!
TTFN,
Jimbo