540 Subfield $a - Terms governing use and reproduction:

Subfield $a contains the terms governing use and reproduction. The terms usually mean the text of a legal or official statement of restrictions.

Examples:

540 ##$aLiterary rights of Carrie Chapman Catt have been dedicated to the public.

540 ##$aRestricted: Information on reproduction rights available at Reference Desk.

540 ##$aRestricted: Copying allowed only for non-profit organizations.