Message = On Rims Trade {anything} the Rims should do the {anything} concentrically 
(if not an 8 dancer Call). What about Hubs Trade {anything}? 
For example: From Waves - Hubs Trade Zing. Is it a normal Zing (to footprints) 
or a concentric Zing (Lines to Lines). Most dancers would do a normal one.
What about Hubs Trade Follow Thru (from Waves). Do the Hubs their Follow Thru 
concentrically, or do all 8 Dancers the Follow Thru. 
That's not very clear from the definition.

Ignore the word 'Concentric'. I should have said something 
like "If the anything call is a 4-dancer (or less) call, 
dancers do the call working with the 4 dancers in the center of the set."

"Hubs Trade Zing" is a normal zing.

"Hubs Trade Follow Thru" (from Waves) would have some dancers crashing
on the same spot. The "Follow Thru" only applies to the new ends.
The caller must say "Concentric" if he/she wants a Concentric Follow Thru.

Sorry for any confusion.