The Convert utilities NDF2IRAF and IRAF2NDF are built using copies of relevant IRAF libraries (which are included in the Convert release) so they exhibit the same behaviour as the IRAF version from which the libraries were extracted. (There are also some IRAF dependencies in the so-called SPP routines of Convert – these originate written in the IRAF SPP language and include header files defining the layout of the IRAF image.) The versions of IRAF2NDF and NDF2IRAF which you use must therefore be compatible with the version of IRAF which you are using.
A new version of the IRAF image format was developed for IRAF Version 2.11 onwards. IRAF Version
2.11 onwards will read either the old or new image formats but will produce the new format by
default. (It can be made to produce old-format images by setting environment variable
Convert contains IRAF V2.11 compatible versions of the SPP routines and the IRAF libraries. If you
are still running IRAF V2.10, set environment variable
oifversion=1 before running NDF2IRAF. (This
includes when running Starlink programs from IRAF cl if an output image is produced by ‘on-the-fly’
Details of which IRAF version libraries are used in Convert will be given in the release notes.