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In this type of document, diagrams are drawn using "blocks" corresponding to trial elements rather than horizontal lines. Trial elements are the various time periods of the trial and we want to emphasize the separate trial elements might otherwise be "hidden" in a single horizontal line. See the Section on Trial Elements (TE), for more information about defining trial elements. In general, the elements of a trial will be fairly clear. However, in the process of working out a trial design, alternative definitions of trial elements may be considered, in which case diagrams for each alternative may be constructed.
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