Plain Language Recommendations
Keyboard focus must never be locked or trapped at one particular page element. The user must be able to navigate to and from all navigable page elements using only a keyboard.If navigation requires more than unmodified arrow, tab keys, or other standard exit methods, the user must be advised of the method for moving focus away.
WCAG 2.0 Recommendations
Guideline 2.1: Keyboard Accessible
Make all functionality available from a keyboard.