blockchain – How do the different implementations of the Bitcoin Cash client know what kind of currency they are processing?

TL; DR: Where in this code Does the SV client discover that it is not processing an ABC blockchain?

This picture I asked my question.

There is a different mutually incompatible couple (I'm assuming anyway) implementations of Bitcoin Cash cryptocurrency client software …

  1. Bitcoin Cash ABC
  2. Bitcon Cash SV

My question assumes that each implementation processes its respective transactions using similar but mutually incompatible blockchain processing rules.

Is it normal to run a Bitcoin Cash SV client implementation on an ABC network of Bitcoin Cash? And vice versa? So, how does an implementation know that the network on which it is running is (in) compatible with your particular processing rules?