[en] The NJOY nuclear data processing system was developed at Los Alamos. It consists of modules to produce neutron and photon pointwise, groupwise and problem oriented cross section libraries. The practical use of this system has shown the need for additional modules for the collapsing of groupwise files, combining of ENDF/B formatted files, separation of one file, plotting of cross sections or differences between two cross section files, combining ACE cross section files etc. Such modules were therefore developed at EIR and are described in the present paper. (author)