Not quite sure exactly what you are asking, but I will have a go at answering anyway. In all cases the inter vehicle socket is wired in parallel with the batteries and the vehicle electrics. On some they are connected directly to the batteries an example being my Combat Engineer Tractor, even when the battery isolator is turned off the socket is still connected to the batteries. On others the socket is connected on the vehicle side of the battery isolator switch, an example being my Scammell Crusader, so with the isolator turned off the socket is also isolated from the vehicle batteries. Obviously on a vehicle without a battery isolator switch the socket is directly connected to the batteries, an example being my US Army 2 1/2 Ton Reo.
There are primarily 2 different types, NATO the type seen on most British / European Military vehicles (the concentric round ones ) and US 2 pin. However there is some cross over due to current capacity some heavier US vehicles use the NATO type and some US 2 pin can be seen used for auxiliary power connection on British / European vehicles.
There is also a plug in adaptor which will convert the 2 pin to the NATO concentric type.