Bill Ackerman (firstname.lastname@example.org)
Before computers, callers worked out choreography by moving “checkers”, sometimes termed “dolls”. A set of checkers had 8 pieces that represented the dancers, usually representing the gender and relationships of the dancers with shape and color coding. The caller then physically pushed the checkers through the motions of the calls to keep track of how the sequence worked. This process was time consuming and error prone. SD is a computer program that performs the same function which greatly speeds up the process of writing and dramatically reduces errors. The program is available free of charge from the website. It has both Windows and Linux versions.