What is the meaning of SDK?
Is SDK can be use to integrate other MS dynamics?Thanks. 
SDK just means Software Development Kit. In Microsoft lingo, it normally just referes to a library of code or DLLs etc. that can be used to build a bugger application, or to integrate with an existing application.
In the NAV world, it normally realates to things like the C/FRONT c++ library that allows you to write C code that interfaces to the NAV database directly. For example you can use the SDK and NAS to interface directly tot he NAV business logic.
I am not sure where C/FRONT will be though when Web Services are released.