Fortran/Versions

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• Fortran66 comments are denoted by the letter 'C' in column 1, while F77 use '*'.
• F77 symbolic names are limited to 6 character lengths, while F90 allows names up to 31 characters long.
• Fortran77 files need 6 spaces before words begin, while Fortran90 doesn't (as it uses the free-form code style).