What is annexure-45?

Hi, 

One of my client is exporter , he purchase all the raw materials and supply this materials to the other manufacturer to manufacture the final products, and the final products will be export ,  now while purchasing raw material he founds that the purchase cost go rise from his margin, as the excise and other applicable taxes are add on it,  so one of his trader advice him to get excise registration no. and also ask for ANNEXURE-45  for not charging of exicse and other taxes, MY QUESTION IS WHAT IS ANNEXURE 45, AND WHAT PROCEDURE CLINET HAVE TO FOLLOW,?    PLEASE GUIDE IN DETAILS,

Thanks