Control_Edit_Format

 A control edit descriptor takes one of the following forms:

    c  nc  cn
   
    c     Is a format code (X, T, TL, TR, SP, SS, S, BN, BZ,
          P, /, '...', "...", Q, \, $, or :).

    n     Is an optional number of character positions.

 The term "n" must be a positive, unsigned, integer constant or a
 variable format expression.

 For all format codes (except P), the value of "n" must be within
 the range 1 through 2147483647 (2**31-1); actual useful ranges may
 be constrained by record sizes (RECL) and the file system.

 The P edit descriptor is an exception to the general control edit
 descriptor syntax.  It is preceded by a scale factor, rather than a
 character position specifier.  The value of "n" for P must be
 within the range -128 to 127.

 Control edit descriptors can be grouped in parentheses and preceded
 by a group repeat specification.