Walrus,
For each event (qualifying, finals), there was an "opener start", where people that are not in the actual competition would do performances. I guess this was to verify that safety, judges, cameras etc are rolling and ok. Sort of a "sound check" if you will.
The athletes that had not signed up for actual competition in a dicipline or had dropped out or something had a change to sign up for these "opener rounds" if they wanted (as well as safety divers, coaches etc). You won't get into the actual competition, but since all the judges are there and it is done "officially", it is my understanding it's a valid performance for AIDA ranking.
Tanya didn't make it to the finals, se made a dive under 100m if I remember correctly. But she gathered her self and dove in the opener round for the women's final, and did the record there (incidentally the surfacing looked very strong from where I was watching). It's my understanding that it won't be considerend a WR because it would have had to been part of the competition or announced as an WR attempt before hand. It sounds silly, but if you think about it, it's much easier to bust a record in an opener round, since basically all the mental stress is gone. I'm not saying it was not impressive, just that there is a reason WR attempts have to be announced and realized on the announced date.
Many athletes didin't realize the potential before, but towards the end alot of "dropped out" athletes started appearing in the opener rounds. I for example opened for static finals and DNF. I figured that if I've traveled all that distance, I might as well get all the experience I can.
Funny thing is, in my DNF round there were only 2 openers. Me and a swimmer. Just before top, the announcer said something like "on lane 1 we have an actual freediver and on lane 2 a swimmer who has never freedived in his life". So there I was, with huge neck weights, paradisia, impressive looking warmup routine, breathup, packing, everything...And diving to 65m or something. And then this swimmer, no experience, no breathup, no equipment, swimming a few laps for warmup goes to 90+ meters...Kind of embarassign
Well, DNF is not really my thing...