BBU	Battery Back-Up: An internal Gel-Cell battery is provided capable of maintaining the unit's microprocessor for up to a 4-hour power outage.
DC	DC Operation: Requires the unit to be powered from a DC source exclusively, typically +12 to +35 VDC.
EX10	External Time Base: Available when a user prefers to reference the clock of an existing source of 10 MHz.
HR	Relay Contact Closure: A contact closure occurs at the top of each Hour. Hour and 1/2 Hour closure may be ordered on some products. Relay contacts are rated at 10-Watts maximum load, 500mA maximum switching current.
NTP6	NTP Time Server: Network Time Protocol Output with IPv6 & Network Control input via Ethernet (10/100Base-T, RJ-45).
OCXO	OCXO: Provides an Oven Controlled Crystal Oscillator.
UL	"UL" Approved Power Supply: The unit is supplied with a UL/CSA approved wall mount power supply (90-264 VAC).