The conditions subject to which, and the form in which, a passport or travel document shall be issued or renewed shall be such as may be prescribed:
Provided that different conditions and different forms may be prescribed for different classes of passports or travel documents or for different categories of passports or travel documents under each such class:
Provided further that a passport or travel document may contain in addition to the prescribed conditions such other conditions as the passport authority may, with the previous approval of the Central Government, impose in any particular case.