The COBOL meta-language describes COBOL syntax.  Meta-language elements
  appear in formats, but they are not part of a source program.

1 - braces

  Braces ({}) indicate that you must select one (but no more than one) of
  the enclosed entries.  If one of the entries contains only reserved
  words that are not key words, that entry is the default option when no
  other entry is selected.

2 - brackets

  Brackets ([]) enclose an optional part of a general format.  When they
  enclose vertically stacked entries, brackets indicate that you can
  select one (but no more than one) of the enclosed entries.

3 - choice_indicators

  If choice indicators, {| |}, enclose part of a general format, you must
  select one or more of the enclosed entries (in any order).  However, no
  entry can be used more than once.

4 - ellipsis

  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.

5 - lowercase_words

  Lowercase words are generic terms.  They indicate entries the
  programmer must provide.  Lowercase words can represent COBOL words,
  literals, PICTURE character-strings, comment-entries, function
  arguments,  or complete
  syntactical entries.

6 - special-character_words

  The following special-character words are not underlined in general
  formats but are required where they appear:

      colon      (:)            single (=) and double (==) equal signs

      period     (.)            left (() or right ()) parenthesis

      plus sign  (+)            left (<) or right (>) angle bracket

      minus sign (-)            single (*) and double (**) asterisk

      slash      (/)

7 - uppercase_words

  Underlined uppercase words are key words.  A key word is required and
  must be spelled correctly when it is included in the source program.

  Uppercase words not underlined are optional.  They serve only to
  improve the source program's readability.