[1] RFC 7809 - Calendaring Extensions to WebDAV (CalDAV): Time Zones by Reference ( 版) <https://tools.ietf.org/html/rfc7809>
[2] RFC 5545 - Internet Calendaring and Scheduling Core Object Specification (iCalendar) ( ()) <https://tools.ietf.org/html/rfc5545#section-3.6.5>
[3] RFC 4791 - Calendaring Extensions to WebDAV (CalDAV) () <https://tools.ietf.org/html/rfc4791#section-4.1>