XOR or ⊕ - a type of logical disjunction on two operands that results in a value of true if the operands, or disjuncts, have opposite truth values. A simple way to state this is "one or the other but not both."
Despite the docs saying to use "systemctl start mysql --wsrep-new-cluster" or "service start mysql --wsrep-new-cluster", the only working way is: service mysql bootstrap