USGF writes first major rules & interpretations book based on FIG code with A,B,C difficulty (USGF Rules for Men 1966-1968.) The book includes extensions for trampoline.
Bob Bollinger invents the Axial Rotation (AR) difficulty system for scoring. AR differs greatly from the ordinal system of FIG in that it derives a numerical difficulty value from a formula based on skill complexity (the number of rotations and twists, and position). The system has been modified over the years, and now differs slightly from the original, but operates in much the same way today. (More information is available from Bob Bollinger’s page at FSU, and the US Gymnastics Hall of Fame.)
The Second Trampoline World Championship is held again in London. Again, the competition is organized as a tournament. The winners are Gary Erwin and Judy Mills. The FIT embraces the AR difficulty system at least partially, using it only for seeding athletes into the brackets. (More information is available from Dagmar Nissen-Munn’s history blog, and the Leigh Hennessey-Robson’s Trampoline Pundit page. Also, see the video from the event.) This event also represents the advent for Tumbling world championships, and Synchronized Trampoline.
The USGF makes a formal bid to become the official governing body for Trampoline in the US. The FIT rejects the USGF bid. (The USGF will later drop trampoline as an event in 1969, with the last NCAA Trampoline event held as an exhibition in 1971.) This may be the event that caused USGF to lose interest in Trampoline, although the main consideration was always recognition by FIG.
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