FRC plans laid the groundwork for the return in 2001 of the Z06
From Wikipedia Chevrolet Corvette page:
"For its first year, the C5 was available only as a coupe, although the new platform was designed from the ground up to be a convertible, which returned in 1998, followed by the fixed-roof coupe (FRC) in 1999. One concept for the FRC was for it to be a stripped-down model with a possible V6 engine (nicknamed in-house as the "Billy Bob"). By 2000 FRC plans laid the groundwork for the return in 2001 of the Z06, an RPO option not seen since Zora's 1963 race-ready Corvette."
All C5 Z06s were fixed roof coupes. And all fixed roof coupes were Z06s (I think!) after 2001. Before 2001 a fixed roof coupe had the same engine as the base corvette. It has a trunk as opposed to a hatch.
Here's a regular coupe
It has a hatch as opposed to a trunk, and a targa top. I personally like the coupe body style better.