Mintmarks For Ancient Roman

I recently bought about 10 uncleaned roman coins off ebay and have been cleaning them for the past few weeks. I finally was able to ID my first of the 10, being from Theodosius I. However, I cannot seem to make out the mintmark, which appears to me as SIVOR or something close to that...I plan on using the dissecting microscope that we have at school in the AP Bio rooms. I don't have an pics yet, my camera's battery is dead and I have the battery charging now...Anyone know of any mintmarks like that? The one I am guessing as of this point is Sirmium, Yugoslavia, as the original seller had said on the page that they were believed to be of a serbian (region) origin and I am 100% sure that it is from theodosius I and depicts a person holding a kneeling captive...I am thinking it might say SIROB, which is what is leading me to believe that it is from Yugoslavia...I will post a pic as soon as possible...thanks to anyone who can offer any help...