The rules of baseball differ slightly from league to league, but in general share the same basic gameplay. There are three major rules codes, which differ only slightly. The official baseball rules govern all professional play in the United States and Canada. The rules are published in book form in North America by the Sporting News, and are available online. Many amateur and youth leagues use the "OBR" with only a few modifications for safety. U.S. collegiate and college-age play is often covered by the baseball rulebook of the NCAA; and U.S. high school and high school-age baseball is governed by the rules of the National Federation of State High School Associations (NFHS). Competitions operated by the International Baseball Federation (IBAF), most leagues outside North America, and youth baseball organizations such as Little League, PONY League, and Cal Ripken League all play under slightly modified versions of the Official Baseball Rules. Below are the rules of the BBSA.