In general formats, the ellipsis (...) allows repetition of a part of
  the format.

  To determine which part of the format can be repeated:

    1)  Find the ellipsis.
    2)  Scanning to the left, find the first right delimiter, either ]
        or }.
    3)  Continuing to the left, find its logically matching left
        delimiter, either [ or {.

  The ellipsis applies to the part of the format between the matched pair
  of delimiters.