Therefore, in 1967 Kaplan and Rubens instituted a poll of experts to determine their bidding preferences (e.g., four-card or five-card majors, strong or weak two-bids, doubles of overcalls negative or for penalty, limit or forcing jump raises, etc.). Solvers were also invited to participate in the poll, but their role was restricted to breaking ties among the experts. The result was Bridge World Standard 1968, now known as BWS 68. There have been three major revisions of the system, in 1984, 1994 and 2001. BWS has always been intended as a platform for answering MSC problems, but also as a system that two experienced players could use if they had never partnered one another. Another use for BWS, perhaps intended in 1967 but never touted as a rationale, is to provide a means of tracking how expert preferences have changed over the years.