From Parallel Waves or a Thar.
As one movement, 1/2 Circulate and Slide (nose-to-nose).
A Thar ends in an opposite-handed Thar; Parallel Waves end in a Thar.
Alternative definition: As one movement, Slip The Clutch & Spread.
Cross By changes a R-H setup to a L-H setup & vice-versa.
Think about moving up to the next dancer, to join the opposite hand.
Ends become Centers and Centers become Ends.
Some callers call Cross By from a 1/4 Tag and want a
Cross Extend [C1].
This usage of Cross By isn't correct since 1/2 Circulate isn't defined from a 1/4 Tag.
According to the CALLERLAB definition: from Parallel Waves Cross By
does not end in a Thar but in a "wave between vertical mini-waves."
This implies that there is a definite resulting
Center Wave. We have never seen any caller try to exploit this aspect.
We believe Cross By from Parallel Waves always ends in a Thar.