What are the rules of tumbling?

• Eight: "Each exercise consists of eight (8) elements."
• One direction: the exercise moves one way only. A single element back the other way is allowed as the eighth.
• No pauses: it is characterised by "continuous speedy, rhythmic hand(s) to feet, and feet to feet, rotational jumping elements without hesitation or intermediate steps".
• The ending: "All completed exercises must end with a somersault", or 2.0 is deducted.
• Into the landing area: the last element goes from the track to the landing area, or 0.4.
• The score: "Score = E (max. 20 pts) + D – P".
• Difficulty: round-offs, flic-flacs, cartwheels and front handsprings 0.1 each, whipbacks 0.2 and each somersault 0.5, with more for twists and positions.
• Doubles and triples: the value of a double somersault is doubled and a triple tripled.
• Interruptions: intermediate steps or stops, a fall, touching outside the track's lines, touching the track with anything but hands or feet and being touched by a spotter.
• Landing penalties: 1.0 for landing outside the lines of the track or landing zone, and 0.2 for stepping out of the landing zone afterwards.
• Start: within 20 seconds of the signal. A springboard may be used for the first element only.
• Repeats: linking elements such as round-offs, flic-flacs and whipbacks may be repeated. Other elements may not, across the two qualifying exercises or the two finals.

The glossary has tumbling, the whipback, the handspring, the somersault, the twist, the tumbling pass and the landing.

Tumbling is speed turned into height: each element has to pass its momentum to the next, so any hesitation both breaks the chain and shows that it was broken. Requiring a final somersault makes every exercise build to something. The one-direction rule is what makes it a pass down a track.