In configuring your EZ-ZONE® PM Temperature Controller, There are a couple of options that present themselves within the Outputs 1, 2, 3 & 4 of the configuration.
Mechanical relay 5A, Form C
Mechanical relay 5A, Form-A
The difference between options Form-C & Form-A are:
Form-C = Is a Single Pole Double Throw (SPDT) contact arrangement with one Normally Open contact (N/O) and one Normally Closed (N/C) contact.
Form-A = Is a Single Pole Single Throw (SPST) Normally Open (N/O) contact.