"Ring Modulation - Sytrus operators can interact not only via FM (frequency modulation) and a simple mix, but also via RM (ring modulation). Ring Modulation is a process where the spectra of two input signals are multiplied together to produce another spectrum, often having characteristics qualitatively different than the input signals. "
Via Create Digital Music. I love Fruity Loops. This one looks really interesting. Title link takes you to the Sytrus link destination off of the Fruity Loops main site. There is a link there to the main Sytrus site. The reason why I'm linking to this interim site is because there is an in depth info section with tons of information on the synth. Make sure to check it out. There are some pretty powerful performance features I haven't seen before. BTW, if anyone knows what RM Synthesis is, please comment. I must have overlooked it on the site.

"Sytrus is a powerful and versatile synthesizer featuring 6 customizable operators for FM and RM synthesis, plucked strings synthesis, 3 SVF (filter) & distortion modules, effects module with chorus effects and 3 delay lines & unique programmable unison mode."
Umm... What's RM synthesis?