Relevance of letter of appointment for a new company

Dear All, 

In the form DIR 12, Attachment contains namely :

(1) Letter of Appointment;
(2) Declaration by the first director
(3) Declaration of the appointee Director,in Form DIR-2; 

Whereas all these 3 attachments are mandatory.

For a new Incorporating Company, Pl explain the relevance of letter of Appointment to the Director from the Proposed Company.

Thanks