You can use the TAB key to navigate the control and its elements you when set the TabIndex property. Pressing the TAB key gets the standard input focus appearance for the control which is a dotted line around the inner border of the item in the control. If C1Calendar is the only control on your Web page then pressing the TAB key again moves focus to C1Calendar's navigation buttons in left to right order from the Quick Previous button to the Quick Next button. If there are multiple controls on your Web page, then pressing the TAB key the second time brings focus to the next control rather than C1Calendar's elements.
When the focus is on any of the navigation buttons, pressing the ENTER key invokes the appropriate action for the selected navigation button. For example, when the focus is on the Previous button, pressing the ENTER key enables you to navigate to the previous calendar month.