What is the Standard RFC (Request For Comments) used by the ZigBee protocol and IEEE 802.15.4?

XBee & XBee Gateway XBee - 802.15.4
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What is the Standard RFC (Request For Comments) used by the ZigBee protocol and IEEE 802.15.4?
Qual é o Padrão RFC (Request For Comments) usada pela ZigBee e o protocolo 802.15.4 IEEE?