I’ve found the following street sign in the wild near a sports stadium:
Is the best way to tag this: parking:left:restriction:conditional=no_parking @ "1 hour before to 1 hour after stadium events" (assuming it is on the left side of the street in this case)
This is what I’ve tended to do, since there isn’t a good mechanism for automatically detecting when the condition would apply even if we make it more structured. I see some scattered usage of @ event and @ special_events in conditional restriction tags. These aren’t technically valid event keywords, but if they were, you could write something like @ (special_event-01:00/special_event+01:00).
By the way, special event regulations aren’t limited to street parking. Here’s a turn restriction in San Francisco that only applies for an indeterminate period of time after the end of baseball games at Oracle Park. (The exact duration is probably spelled out in a city ordinance, but I haven’t bothered to look it up.) For the restriction relation, I just put the text of the restriction in a comment, other than the exception for taxis.
