Where can I find my MAC ID and MAC CRC codes needed for registration?
The MAC ID and MAC CRC will scroll in the message center of the thermostat. The numbers are also printed on the Thermostat ID Card included in the thermostat package, and they can also be found on the back of the thermostat when it is removed from the wallplate. Each thermostat has a unique MAC ID and MAC CRC. (Page 60)
From the official Honeywell RET97B5D100 Home Programmable Thermostat manual, page 60
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