Label "d" in the first column, Fortran 77

Question

I am modifying the code from a model written in Fortran 77, but the strange thing occurred to me. In some files, the first column of the row has a label “d”, as in the example below:

d     real*8    co2rootfix,co2rootloss,co2shootfix
d     character komma*1

d     open(unit=87,file='crop_CO2.csv',status='unknown')
d     write(87,*) 'date,co2rootfix,co2rootloss,co2shootfix'
d     open(unit=88,file='crop_dm.csv',status='unknown')
d     write(88,*) 'date,wrtpot,wrt,wstpot,wst,rdpot,rd,laipot,lai,
d    &gwrt,gwst,drrt,drlv,drst'

It is strange that it is successfully compiled by the Intel ifort compiler. However, gfortran logically returns the following error:

Error: non-numeric character in operator label in (1)

I'd like to know:

• the value of this label;
• why is it only recognized ifort and
• How can I make it work with gfortran.

Answer 1

The ifort documentation has options -d-linesand -nod-lines:

. , , D 1 ( ), .

, -d-lines ( -nod-lines, ), d .

gfortran -fd-lines-as-code -fd-lines-as-comments . , ifort, , ( , -nod-lines). gfortran , .