TTOR (Topological Transaction Ordering) is used by Bitcoin and Bitcoin Cash pre-CTOR. In TTOR, there may be several possible ways to order transactions. The only requirement is that the chain of transactions must be ordered by time and the base transaction of currencies must be the first.
Let's say that there are transactions A, B, and C, and suppose that there is no base currency transaction. A and B are common transactions, but C spends at least one exit from B. Possible orders are:
A B C B A C B C A
Amaclin is right, SegWit did not change anything related to them.