6.1.25 Form feed as whitespace
Historically, legacy compilers allowed insertion of form feed characters (’\f’, ASCII 0xC) at the beginning of lines for formatted output to line printers, though the Fortran standard does not mention this. GNU Fortran supports the interpretation of form feed characters in source as whitespace for compatibility.
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https://gcc.gnu.org/onlinedocs/gcc-8.4.0/gfortran/Form-feed-as-whitespace.html