Johnson Controls AIM-200 Technical Manual page 8

A77-716-02B
The end-of-line power supervision relay is used to supervise the power
to 4-wire smoke detectors and indicting appliances.
N-ELR
The N-ELR resistor assortment is required for use in Canada. It
provides a variety of resistor values to mount to a single ELR plate
(included). Resistors can be used for the supervision of an M500MJ
monitor module or M510CJ control module circuit.
Resistors included:
120 ohms, 470 ohms, 1.8K, 2.2K, 4.7K, 6.8K, 10K, 27K, and 47K.
8 Addressable Intelligent Module—AIM -200 Addressable Intelligent Module