time zones

This document specifies the Time Zone Information Format (TZif) for representing and exchanging time zone information, independent of any particular service or protocol. Two media types for this format are also defined.

This document replaces and obsoletes RFC 8536.

This document defines an extension to the timestamp format defined in RFC 3339 for representing additional information, including a time zone.

It updates RFC 3339 in the specific interpretation of the local offset Z, which is no longer understood to "imply that UTC is the preferred reference point for the specified time".

This document defines a time zone data distribution service that allows reliable, secure, and fast delivery of time zone data and leap-second rules to client systems such as calendaring and scheduling applications or operating systems.

This document defines an update to the Calendaring Extensions to WebDAV (CalDAV) calendar access protocol (RFC 4791) to allow clients and servers to exchange iCalendar data without the need to send full time zone data.

Time zone information serves as a basic protocol element in protocols, such as the calendaring suite and DHCP. The Time Zone (TZ) Database specifies the indices used in various protocols, as well as their semantic meanings, for all localities throughout the world. This database has been meticulously maintained and distributed free of charge by a group of volunteers, coordinated by a single volunteer who is now planning to retire. This memo specifies procedures involved with maintenance of the TZ database and associated code, including how to submit proposed updates, how decisions for inclusion of those updates are made, and the selection of a designated expert by and for the time zone community. The intent of this memo is, to the extent possible, to document existing practice and provide a means to ease succession of the database maintainers. This memo documents an Internet Best Current Practice.

Two common ways to communicate timezone information are POSIX 1003.1 timezone strings and timezone database names. This memo specifies DHCP options for each of those methods. The DHCPv4 time offset option is deprecated. [STANDARDS-TRACK]