But it's describing exactly what it is - half of a Saver return. The official ruling is that it's only valid with AP on the other "portion" mind....
it is only ISSUED with an AP on the other portion.
You cannot say it is only valid with the other portion! As
1) the only ticket type to claim that is the SOR (outward only valid with intact rtn portion), and
2) aren't Saver half returns only for the rtn portion? (I am not sure on this), in which case how can you required to be in posession of a ticket for a journey that has ceased? the barriers could have swallowed it anyway, and
3) it would rather destroy the whole purpose of advance singles.
The Saver Half is, effectively, a single that happens to only be issued in conjunction with an AP single. The reason for the naming is because Saver Singles are about 5-10p less than Saver returns, and also Saver Singles only have a validity of 1 day, compared to the rtn portion of 1 month.