I just saw JB's posting and heartily agree with the suggestion to go on-line. Our school's policies are clearly stated there. In fact, if your school has a gifted teacher, then he or she would have a web page that should address this issue, hopefully? They should at least talk about MAP scores and what they mean.
If you already have a child in the gifted program, then perhaps you already know some of these answers? I'm speaking from the point of view of a first-time parent who is fighting the system. You may be ahead of the game if you already have one child in the pipeline. You just need an upgrade on your services to your pipeline!!