If the amount appropriated (or made available in the event of a sequestration order issued pursuant to the Balanced Budget and Emergency Deficit Control Act of 1985 (Public Law 99–177; [2 U.S.C. 900 et seq.])) for a fiscal year pursuant to any authorization of appropriations provided by an Act other than an appropriation Act is less than the authorization amount and a provision of that Act provides that a specified amount of the authorization amount shall be available only for a certain purpose, then the amount so specified shall be deemed to be reduced for that fiscal year to the amount which bears the same ratio to the specified amount as the amount appropriated (or made available in the event of sequestration) bears to the authorization amount.