It is claimed that, after

Set rng = Range("C1:C3")

with no variable declaration, rng is a Variant containing a Range type
variable of the same name, rather than that rng is simply a Range type
variable.

1. How can this claim be tested?

2. Under what circumstances would it ever make a difference?

Simply using Typename to resolve the difference is not definitive,
because part of the claim is that Typename(rng) returns the type of the
Range type variable within the Variant rather than the type of the Variant.

Alan Beban