Chris ...

^ Frank, you are correct about "rolling" meaning a vehicle
^ being followed by the scout car. It has a different meaning
^ than "roller".

This jargon must have a different meaning in our two areas. A "roller" in
California has always been a request for a 10-28/1-29 on a moving vehicle --
one that has not yet been stopped. It's used by patrol officers. The term is
used as follows:

UNIT: Paul 6 with a roller. (Or ... clear for a roller?)
DISPATCH: Go ahead.
UNIT: California 9ABC876.
DISPATCH: No wants, registration is current to a ...

In years past the term was used as "Paul 6, rolling 28/29 on California
9ABC876" but the term is now so common in the state that it's been condensed
to just "roller" in many areas.

Frank