Calling races as another political convention, like concessions

The other day I wrote about how concessions in US political races are a matter of convention, not law. And the media announcements of winners before the results are finalized (like CNN and others calling the presidential race today) are also conventions that have no effect on the results if they ultimately turn out otherwise. But the flip side of such conventions as concessions and the calling of races is that, even if they can be overturned, they become part of the system, the rules by which the game is played. Donald Trump has broken such conventions throughout his political career and presumably isn't going to abide by them now, either. (Andrew Shields, #111words, 7 November)