Also, re: question posted earlier -- to my knowledge, teams from same league are allowed to be placed in First Four matchup, although I'm guessing committee would try to avoid it if possible. But maybe there is a rule they can't meet if they've played more than once in regular season, unless unavoidable (not sure on that one, without checking).
Each of the first four teams selected from a conference shall be placed in different regions if they are seeded on the first four lines.
Teams from the same conference shall not meet prior to the regional final if they played each other three or more times during the regular season and conference tournament.
Teams from the same conference shall not meet prior to the regional semifinals if they played each other twice during the regular season and conference tournament.
Teams from the same conference may play each other as early as the second round if they played no more than once during the regular season and conference tournament.
Any principle can be relaxed if two or more teams from the same conference are among the last four at-large seeded teams participating in the First Four.