[AnimalMuppet]

I believe that your understanding is correct.

   template <typename T>

is a template with one "type parameter" (may not be the correct technical term), whereas

   template <typename T, typename U>

is a template with two type parameters, and they can be different. (That's why you give two parameters, so that they don't have to be the same.)

[gryfft]

I appreciate the sanity check with a depth and viscerality I can't properly express.

I also apologize to you and anyone reading for any inaccurate terminology on my part.