¹The Master and Synchronized bits together provide information on how closely the Time attribute conforms to the time standard.

The Master bit specifies whether the real time clock corresponding to the Time attribute is internally set to the time standard. This bit is not writeable – if a value is written to the TimeStatus attribute, this bit does not change.

The Synchronized bit specifies whether Time has been set over the ZigBee network to synchronize it (as close as MAY be practical) to the time standard (see 3.12.1). This bit must be explicitly written to indicate this – i.e., it is not set automatically on writing to the Time attribute. If the Master bit is 1, the value of this bit is 0.

If both the Master and Synchronized bits are 0, the real time clock has no defined relationship to the time standard (e.g., it MAY record the number of seconds since the device was initialized).

The MasterZoneDst bit specifies whether the TimeZone, DstStart, DstEnd and DstShift attributes are set internally to correct values for the location of the clock. If not, these attributes need to be set over the network. This bit is not writeable – if a value is written to the TimeStatus attribute, this bit does not change.

Devices SHALL synchronize to a Time server with the highest rank according to the following rules, listed in order of precedence:

- A server with the Superseding bit set SHALL be chosen over a server without the bit set.
- A server with the Master bit SHALL be chosen over a server without the bit set.
- The server with the lower short address SHALL be chosen (note that this means a coordinator with the Superseding and Master bit set will always be chosen as the network time server).
- A Time server with neither the Master nor Synchronized bits set SHOULD not be chosen as the network time server.

Zigbee Alliance (2015, 03, 18). Zigbee Cluster Library Specification - R5.

*Permission is granted to members of the ZigBee Alliance to reproduce this document for their own use or the use of other

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