The only thing that I can come up with is this link:
http://www.natlaw.com/interam/first.htm
"The National Law Center for Inter-American Free Trade’s InterAmSM Database is an on-line collection of laws, regulations, case law, and secondary source materials for countries in the Americas."
It could be the date that the Source Material database was checked and instead of writing out in full InterAmSM Database after the date they just add "SM". Sorry it's not much to go on but I suppose it could be a possibility.