I'm not sure what is the point of this summary. The rules in effect at the date and place of purchase of the OWE ticket apply for the life of the ticket (this is why the ailrines must keep multiple sets of rules in their computer system).

For example, for OWE bought in SWP, a trans-oceanic surface sector is allowed. So all of the continent transitions can potentially be by surface. While this is not the rule for other OWE tickets. There are a dozen such special cases.

The real impact is that some routings can only be done westbound and not eastbound. MRU origin with MRU-LHR as the first leg must go westbound if wanting to return to MRU (as the 2nd entry into Europe is not allowed), for example.

The bottom line is that all the rules must be considered for any particular routing, and "rule of thumb" rules like this summary are indicative but not specific enough to determine whether a routing is legal or not. Adding all the exceptions makes it the same as the original rules (which are only a few hundred lines long, so not that complex).