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The following diagram for a crossover trial does not use the crossing slanted lines sometimes used to represent crossover trials, because the order of the blocks is sufficient to represent the design of the trial. Slanted lines are used only to represent the branch point at randomization, when a subject is assigned to a sequence of treatments. As in most crossover trials, the arms are distinguished by the order of treatments, with the same treatments present in each arm. Note that even though all 3 arms of this trial end with the same block (i.e., the block for the follow-up element), the diagram does not show the arms converging into one block. Also note that the same block (the "rest" element) occurs twice within each arm. Elements are conceived of as "reusable" and can appear in more than 1 arm, in more than 1 epoch, and more than once in an arm.

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