Ms, Miss, Mrs or Mdm?

On many of our registration forms, there's always a column that requires you to tick either Ms., Miss, Mrs or Madam. I've always wondered what is the difference between Ms. and Miss? Isn't Ms. the short form of Miss? Then there comes further complications for married women. If you are a married woman and have a first name which is an English name, which column are you supposed to tick? You can't very well be Ms. (or Miss) something because you're married. So you're supposed to be Mrs. something but it's not right to put Mrs. in front of your own English name followed by your family name. You can use Mdm. but that sounds so old. So, then you want to put Mrs. first English name followed by your married surname. That's when the form has a clause which says "name must be as per your NRIC or passport".

So what is it then?