https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92350
--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> ---
Just found:
gfortran.texi – Extensions to namelist
When writing a namelist, if no @code{DELIM=} is specified, by default a
double quote is used to delimit character strings. If -std=F95, F2003,
or F2008, etc, the delim status is set to 'none'. Defaulting to
quotes ensures that namelists with character strings can be subsequently
read back in accurately.
This might be sufficient or the wording can be improved. Hence, one can also
close PR again.