Catherine Moroney wrote: > how much Fortran90 understanding > does the current version of the g77 compiler have? I have not seen exact documentation, but the answer is: very little. Mostly some syntactic sugar like REAL :: i instead of only real i and nothing that really requires significant implementation support, like modules, array syntax, derived types, etc. So unless it is a Fortran 77 code to begin with, forget about porting it to g77! Aleks