Confuse Sigma

I am looking into a Sigma 50mm f1.4. I am confused because some website discribes this lens as 50mm f1.4 EX DG HSM for Four Thirds System. Some website describes this as 50 f1.4 EX DG HSM for the full frame. Is there actually 2 different version of this 50mm lens? Thanks for your help.

full frame.

New Sigma lens for the Four Thirds system. sorry.

According to the info on this site this lens is available for all sorts of mounts including 4/3 but I was under the impression is was full frame on those mounts which have a full frame option.

There is also a 30mm f1.4 Sigma.