In free source form, statements are not limited to specific
  positions on a source line, and a line can contain from 0 to 132
  characters.

  Blank characters are significant in free source form.  The
  following are rules for blank characters:

   o  Blank characters must not appear in lexical tokens, except
      within a character context.  For example, there can be no
      blanks between the exponentiation operator **.  Blank
      characters can be used freely between lexical tokens to improve
      legibility.

   o  Blank characters must be used to separate names, constants, or
      labels from adjacent keywords, names, constants, or labels.
      For example, consider the following statements:

        INTEGER NUM
        GO TO 40
        20 DO K=1,8

      The blanks are required after INTEGER, TO, 20, and DO.

   o  Some adjacent keywords must have one or more blank characters
      between them.  Others do not require any; for example, BLOCK
      DATA can also be spelled BLOCKDATA.  The following list shows
      which keywords have optional or required blanks.

      Optional Blanks           Required Blanks
      ----------------          ----------------
      BLOCK DATA                CASE DEFAULT
      DOUBLE COMPLEX            DO WHILE
      DOUBLE PRECISION          IMPLICIT type
      ELSE IF                   IMPLICIT NONE
      END BLOCK DATA            INTERFACE ASSIGNMENT
      END DO                    INTERFACE OPERATOR
      END FILE                  MODULE PROCEDURE
      END FORALL                RECURSIVE FUNCTION
      END FUNCTION              RECURSIVE SUBROUTINE
      END IF                    RECURSIVE type FUNCTION
      END INTERFACE             type FUNCTION
      END MODULE                type RECURSIVE FUNCTION
      END PROGRAM
      END SELECT
      END SUBROUTINE
      END TYPE
      END WHERE
      GO TO
      IN OUT
      SELECT CASE

  The exclamation point character (!) indicates a comment if it is
  within a source line, or a comment line if it is the first
  character in a source line.

  The ampersand character (&) indicates a continuation line (unless
  it appears in a Hollerith or character constant, or within a
  comment).  The continuation line is the first noncomment line
  following the ampersand.  Although Fortran 95/90 permits up to 39
  continuation lines in free-form programs, VSI Fortran allows up
  to 511 continuation lines.

  The following shows a continued statement:

  TCOSH(Y) = EXP(Y) + &        ! The initial statement line
             EXP(-Y)           ! A continuation line

  If the first nonblank character on the next noncomment line is an
  ampersand, the statement continues at the character following the
  ampersand.  For example, the preceding example can be written as
  follows:

  TCOSH(Y) = EXP(Y) + &
            & EXP(-Y)

  If a lexical token must be continued, the first nonblank character
  on the next noncomment line must be an ampersand followed
  immediately by the rest of the token.  For example:

  TCOSH(Y) = EXP(Y) + EX&
            &P(-Y)

  If you continue a character constant, an ampersand must be the
  first non-blank character of the continued line; the statement
  continues with the next character following the ampersand.  For
  example:

  ADVERTISER = "Davis, O'Brien, Chalmers & Peter&
                   &son"
  ARCHITECT  = "O'Connor, Emerson, and Davis&
                   & Associates"

  In VSI Fortran, if the ampersand is omitted on the continued
  line, the statement continues with the first non-blank character in
  the continued line.  So, in the preceding example, the whitespace
  before "Associates" would be ignored.

  The ampersand cannot be the only nonblank character in a line, or
  the only nonblank character before a comment; an ampersand in a
  comment is ignored.