PGI Fortran Reference manual - The Portland Group

Language Overview1.4.5. Fixed Format Debug StatementsThe letter D in column 1 using fixed formatting designates the statement on the specified lineis a debugging statement. The compiler treats the debugging statement as a comment, ignoringit, unless the command line option –Mdlines is set during compilation. If –Mdlines is set,the compiler acts as if the line starting with D were a Fortran statement and compiles the lineaccording to the standard rules.1.4.6. Tab FormattingThe PGI Fortran compilers support an alternate form of fixed source from called tab source form.A tab formatted source file is made up of a label field, an optional continuation indicator and astatement field. The label field is terminated by a tab character. The label cannot be more than 5characters.A continuation line is indicated by a tab character followed immediately by a non-zero digit. Thestatement field starts after a continuation indicator, when one is present. Again, any charactersfound beyond the 72nd character, or position 132 if –Mextend is specified, are ignored.1.4.7. Fixed Input File Format SummaryFor fixed input file format, the following is true:‣ Tab-Format lines are supported.‣ A tab in columns 1-6 ends the statement label field and begins an optional continuationindicator field.‣ If a non-zero digit follows the tab character, the continuation field exists and indicates acontinuation field.‣ If anything other than a non-zero digit follows the tab character, the statement bodybegins with that character and extends to the end of the source statement.This does not override Fortran's free source form handling since no valid Fortran statement canbegin with a non-zero digit.‣ The tab character is ignored if it occurs in a line except in Hollerith or characterconstants.‣ Input lines may be of varying lengths.‣ If there are fewer than 72 characters, the line is padded with blanks.‣ Characters after the 72nd are ignored unless the –Mextend option is used on thecommand line.The –Mextend option extends the statement field to position 132.When the –Mextend option is used, the input line is padded with blanks if it is fewerthan 132 characters; characters after the 132nd are ignored.‣ Blank lines are allowed at the end of a program unit.PGI Fortran Reference Guide 6