At the time (1990s) we had thought this was a uniquely North Korean activity, but a quick Google search just now turned this up (abridged):  “Dance notation is the symbolic representation of human dance movement and form, using graphic symbols and figures, path mapping, numerical systems, and letter and word notations. Several dance notation systems have been invented, many of which are designed to document specific types of dance while others have been developed with capturing the broader spectrum of human movement potential.”   Perhaps not many countries build an entire tour around it as the Koreans did, though.  Trust us:  it was complicated.  Grade: 1