Thanks for the replies. I talked to the AHJ and he said he would not approve it unless I could confirm the 100A breaker was listed for use in the 200A panel. He didn't think it would be. It is a QO 200A panel. First, no one in my immediate area had a 100A QO main breaker and on further inspection the two breakers are different size physically and it looks like it would not fit anyway. I did email Schneider Electric, who bought out Square D several years ago, to ask about the listing but so far have not received a response. So anyway, I am running 4/0 Al instead.