# Free Source Form

In free source form, statements are not limited to specific positions on a source line. In Standard Fortran, a free form source line can contain from 0 to 132 characters. Intel® Fortran allows the line to be of any length.

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

- 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.

- 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.

- 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 | ABSTRACT INTERFACE
  DOUBLE COMPLEX | CASE DEFAULT
  DOUBLE PRECISION | CHANGE TEAM
  ELSE IF | CLASS DEFAULT
  ELSE WHERE | CLASS IS
  END ASSOCIATE | DO CONCURRENT
  END BLOCK | DO WHILE
  END BLOCK DATA | ERROR STOP
  END CRITICAL | EVENT POST
  END DO | EVENT WAIT
  END ENUM | FAIL IMAGE
  END FILE | FORM TEAM
  END FORALL | IMPLICIT type-specifier
  END FUNCTION | IMPLICIT NONE
  END IF | INTERFACE ASSIGNMENT
  END INTERFACE | INTERFACE OPERATOR
  END MODULE | MODULE PROCEDURE
  END PROCEDURE | prefix 1 [prefix …] FUNCTION
  END PROGRAM | prefix 1 [prefix …] type-specifier [prefix...] FUNCTION
  END SELECT | prefix 1 [prefix …] SUBROUTINE
  END SUBMODULE | SYNC ALL
  END SUBROUTINE | SYNC IMAGES
  END TEAM | SYNC MEMORY
  END TYPE | SYNC TEAM
  END WHERE | type-specifier FUNCTION
  GO TO | type-specifier prefix 1 [prefix …] FUNCTION
  IN OUT |
  SELECT CASE |
  SELECT TYPE |
  1prefix is ELEMENTAL or IMPURE or MODULE or NON_RECURSIVE or PURE or RECURSIVE. No prefix can be specified more than once. You cannot specify both IMPURE and PURE. You cannot specify both NON_RECURSIVE and RECURSIVE.

For information on statement separators (;) in all forms, see Source Forms.

## Comment Indicator

In free source form, 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.

## Continuation Indicator

In free source form, 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 Standard Fortran permits up to 256 continuation lines in free-form programs, Intel® 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 Dickinson&
            &  Associates"

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.

## See Also

Source Forms for details on the general rules for all source forms