RIS is a standardized tag format developed by Research Information Systems, Incorporated (the format name refers to the company) to enable citation programs to exchange data.
The bibutils program set interconverts between various bibliography formats using a common MODS-format XML intermediate. For example, one can convert RIS-format files to Bibtex by doing two transformations: RIS->MODS->Bibtex. By using a common intermediate for N formats, only 2N programs are required and not N²-N. These programs operate on the command line and are styled after standard UNIX-like filters.