This document specifies a new iCalendar calendar component that allows the publication of available and unavailable time periods associated with a calendar user. This component can be used in standard iCalendar free-busy lookups, including iTIP free-busy requests, to generate repeating blocks of available or busy time with exceptions as needed. This document also defines extensions to CalDAV calendar-access and calendar-auto-schedule which specify how this new calendar component can be used when doing free-busy time evaluation in CalDAV.