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Sequence of locations xp of the pair of trucks relative to shell crown_
| xp/L | –4/4 | –3/4 | –2/4 | –1/4 | 0 | 1/4 | 2/4 |
|---|---|---|---|---|---|---|---|
| Primary travel | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
| Secondary travel | – | 11 | 10 | 9 | 8 | 7 | 6 |