The General Clauses Act, 1897
§21 — Power to issue, to include power to add to, amend, vary or rescind notifications, orders, rules or bye-laws
Where, by any [Central Act] or Regulations a power to [issue notifications,] orders, rules or bye-laws is conferred, then that power includes a power, exercisable in the like manner and subject to the like sanction and conditions (if any), to add to, amend, vary or rescind any [notifications,] orders, rules or bye-laws so [issued].