No. That part very much definitely is there. The players absolutely have the right to know how hard the difficulty will be before they call for the roll. Fictionally if nothing else. Calling out the TN in advance is not in there. That’s just an easy way of fulfilling the GM obligation to signal the difficulty.

One thing I’ve noticed in your write-ups is that you tend to treat the rules like boardgame rules…something I’m entirely sympathetic to as both of the games I’ve published are written to be read that way. But they’re the only two I know of that are…well maybe Moldvay D&D (which is why its the only version of basic that you can actually play as written).

But most games aren’t written that strictly. Just because there is a list of numbered steps and in that list “determine TN” comes after “call for the roll” that doesn’t actually mean that. There are almost no RPGs written where (in the absence of specific direction to do so) you can take the rules that literally.

The text surrounding that list makes it pretty clear that all rolls are made at the default TN unless the GM has a very good reason to say otherwise…and that very good reason had better be reflected in the fiction leading up to the situation where the player calls for the roll.

I went back and read that section, that’s hammered pretty hard.