@cindex language, dialect options
@cindex options, dialect
-The following options control the dialect of Fortran
-that the compiler accepts:
+The following options control the details of the Fortran dialect
+accepted by the compiler:
@table @gcctabopt
@cindex -ffree-form option
@item -ffixed-form
Specify the layout used by the source file. The free form layout
was introduced in Fortran 90. Fixed form was traditionally used in
-older Fortran programs.
+older Fortran programs. When neither option is specified, the source
+form is determined by the file extension.
@cindex -fall-intrinsics
@item -fall-intrinsics
@cindex -fd-lines-as-comments, option
@item -fd-lines-as-code
@item -fd-lines-as-comment
-Enables special treating for lines with @samp{d} or @samp{D} in fixed
-form sources. If the @option{-fd-lines-as-code} option is given
-they are treated as if the first column contained a blank. If the
+Enable special treatment for lines beginning with @samp{d} or @samp{D}
+in fixed form sources. If the @option{-fd-lines-as-code} option is
+given they are treated as if the first column contained a blank. If the
@option{-fd-lines-as-comments} option is given, they are treated as
comment lines.
@cindex option, -fdefault-double-8
@cindex -fdefault-double-8, option
@item -fdefault-double-8
-Set the "DOUBLE PRECISION" type to an 8 byte wide.
+Set the @code{DOUBLE PRECISION} type to an 8 byte wide type.
@cindex option, -fdefault-integer-8
@cindex -fdefault-integer-8, option
@item -fno-backslash
@cindex backslash
@cindex escape characters
-Compile switch to change the interpretation of a backslash from
-``C''-style escape characters to a single backslash character.
+Change the interpretation of backslashes in string literals from
+``C-style'' escape characters to a single backslash character.
@cindex -ffixed-line-length-@var{n} option
@cindex options, -ffixed-line-length-@var{n}
@cindex card image
@cindex extended-source option
Popular values for @var{n} include 72 (the
-standard and the default), 80 (card image), and 132 (corresponds
+standard and the default), 80 (card image), and 132 (corresponding
to ``extended-source'' options in some popular compilers).
-@var{n} may be @samp{none}, meaning that the entire line is meaningful
+@var{n} may also be @samp{none}, meaning that the entire line is meaningful
and that continued character constants never have implicit spaces appended
to them to fill out the line.
@option{-ffixed-line-length-0} means the same thing as
@cindex free form
@cindex limits, lengths of source lines
Set column after which characters are ignored in typical free-form
-lines in the source file. For free-form, the default value is 132.
+lines in the source file. The default value is 132.
@var{n} may be @samp{none}, meaning that the entire line is meaningful.
@option{-ffree-line-length-0} means the same thing as
@option{-ffree-line-length-none}.
@cindex option -fmax-identifier-length=@var{n}
@item -fmax-identifier-length=@var{n}
Specify the maximum allowed identifier length. Typical values are
-31 (Fortran 95) and 63 (Fortran 200x).
+31 (Fortran 95) and 63 (Fortran 2003).
@cindex -fimplicit-none option
@cindex options, -fimplicit-none
@cindex -fcray-pointer option
@cindex options, -fcray-pointer
@item -fcray-pointer
-Enables the Cray pointer extension, which provides a C-like pointer.
+Enable the Cray pointer extension, which provides C-like pointer
+functionality.
@cindex -fopenmp
@cindex options, -fopenmp
@item -fopenmp
-Enables handling of OpenMP @code{!$omp} directives in free form
+Enable the OpenMP extensions. This includes OpenMP @code{!$omp} directives
+in free form
and @code{c$omp}, @code{*$omp} and @code{!$omp} directives in fixed form,
-enables @code{!$} conditional compilation sentinels in free form
-and @code{c$}, @code{*$} and @code{!$} sentinels in fixed form
+@code{!$} conditional compilation sentinels in free form
+and @code{c$}, @code{*$} and @code{!$} sentinels in fixed form,
and when linking arranges for the OpenMP runtime library to be linked
in.
@cindex -std=@var{std} option
@cindex option, -std=@var{std}
@item -std=@var{std}
-Conform to the specified standard. Allowed values for @var{std} are
-@samp{gnu}, @samp{f95}, @samp{f2003} and @samp{legacy}.
+Conform to the specified standard. The default value for @var{std} is
+@samp{gnu}; a superset of the Fortran 95 standard which includes all
+of the GNU extensions recommended for use in new code. The @samp{legacy}
+value also includes obsolete extensions that may be required for old
+non-standard programs. Strict conformance to the Fortran 95 and Fortran 2003
+standards is specified by @samp{f95} and @samp{f2003}, respectively.
@end table