Mexican law provides that only Mexicans can own coastal real estate. In the early 1970s, Mexico's government realized that allowing foreigners to purchase real estate in these coastal areas would benefit Mexico's economy; so they provided that a foreigner could have a beneficial interest in a Fideicomiso or "Mexican Trust."  
Now that PLR 104521-12 has been released by the IRS and Amy Jetel, the attorney who requested the PLR has written an article Fedeicomisos: Clarity at Last which not only analyzes this PLR as it relates to Mexican Fideicomiso, but also provides insight on how the IRS will review other trusts .