When jack socket #2 is not in use, the "tip" of jack socket # 2 is shorted to the "ring" of jack socket #1, and also the "ring" of jack socket # 2 is shorted to the "sleeve" of jack socket #1.
These connections are interrupted as soon as a jack is inserted into jack socket #2.
If jack socket #1 is used with a TRS jack and stereo cable - both footswitch #1 and footswitch #2 (relays 1+2) can be used to independently control the status of the TS & RS connections (open/ closed) - thereby allowing the user to switch 2 "analog" functions from the FCB1010 using one TRS cable. This may be of use, say, for an amplifier in which you can switch "channel" & "effect on/off".
If the second jack is used, this capability is defeated.
The SWITCH OUT jacks on the FCB1010 are the latching type, and amps like our GX110 and GX112 use the momentary type, which require 2 taps on the switch to access the function, instead of one tap.