group developed a higher-level Fortran interface for IRAF called F77VOS (Fortran 77/IRAF Virtual Operating System). The F77VOS interface has a set of image subroutines similar to those in IMFORT, but they can access data in both the IRAF OIF and STSDAS GEIS formats. Also, F77VOS provides subroutines libraries that allow Fortran programs to be fully integrated with the IRAF environment. You can read and write parameters in the IRAF CL, send text messages to the user, do standard graphics, and read and write data in STSDAS tables. Because F77VOS programs are fully layered on the IRAF VOS, they must be run from the IRAF CL.
The F77VOS interface is described in the document A Fortran 77 Interface for IRAF, which is available from the STSDAS group at STScI.