How change tracking feature of msWord can be implemented using C#.NET?

Question

1. Is microsoft word 2003 file format available to public? If yes, where? If no, is it possible to get it?

2. To implement change tracking technique of msword 2003 through C#.NET, is it necessary to know file format? If not, how it can be implemented?

This information is needed for research in post graduation. So kindly help me for the same.
Thank you.