The Dallas Motion Picture Classification Board has tagged Columbia’s “Last Action Hero” with its “not suitable” rating. It is the Dallas board’s sternest advisory, applied to films its members consider unsuitable for reasons of content for those under the age of 16.The decision comes too late for Columbia to appeal the rating before the Arnold Schwarzenegger starrer opens today with roughly 2,300 playdates. According to a city official, Columbia has warned of “potential litigation.” A studio spokesman declined comment. However, a source at Columbia said there was no suit in the offing. He said that most Dallas exhibitors follow Motion Picture Assn. of America ratings because the local board ratings are purely advisory. One of the largest municipal ratings boards in the U.S. that does not use MPAA ratings, Dallas screened the film one week ago. Kathy Toler, the city administrative assistant responsible for the board, said roughly 20 members were involved in the decision.