This "quick tutorial" introduces the general idea of a call and explains the most common cases. It does not explain or illustrate all cases. For additional details and/or examples, refer to the links in the "MORE INFO" box.
For example, it may be that only four of the dancers can do the first part and the second part. While they are doing that, the other four dancers must wait. Then everybody can do the third part.
Or it may be that everybody can do the first part and the second part, but only four of the dancers can do the third part. In this case, the dancers who can't do the third part must wait while the others complete the call.