As far as I know the State does not have a State Building Code as yet, every jurisdiction may have their own Code. The Attorney General ruled that the State Energy Code only applies to State Public Buildings. Until the MS Depart of Economic Development adopts the Energy it is not a State Code. The Counties and Cities regarding a Building Code can opt out of the State's suggested Building Code that was passed which is what I think you are referencing. However, the State Fire Marshall and the BOB use the ICC 2012 editions. The BOB is for only State projects. Fire Marshall has jurisdiction over those areas that do not have a building code especially Assembly and only goes out when there is a problem. It's still Good Ole Boy Politics here. You will need to call the local government to see what Building Code, if any they use and any amendments they did to the Codes every time you start a project. You may can get better info from the MS Board of Architecture. I work with one of the Board Members and we discuss Code laws frequently.