Purpose of form 16?

It is given by employer to employee and indicates that employer has deposited that much amount which is mentioned on the certificate with the  tax authorities. It also has details of amount paid in it by employer to employee.

Form 16 is certificate of TDS.  

Yes, while filiing return we will consider 26AS because it has details of total tax credit available to the assessee which is deducted from various source of income. Form 16 declares TDS from salary only. In case, there is an error in Form 16, employee can ask employer to rectify it since it is the employer who has generated it for employee.

Suppose Mr A started working in december. At that time he didn't have a PAN. So, he provided PAN to the company only in Jan. The company has deducted TDS for all moths (even though below taxable limit). And the company now informs him that Form 16 will be issued to him only from January, since PAN for earlier period was not provided. Is the company required to revise his return? What should Mr. A do?