There isnt any hard n fast rule...like LKO isnt Jn while CNB/SPN line branch-off just after LKO...controlled by LKO Signalling...
While GKP/FD-SLN/PBH line branch off just b4 Dilkusha (although Dilkusha isnt any station bt acts as controlling point for this branch off)..bt still technically, its after LKO & b4 any other station where branching hppns....