> AFAICT it's just noise, perhaps once meant to remind you that you're
> looking at an interval rather than an absolute time. Thomas, any
> recollections here?
The leading "@" is by now a historical artifact (and was at the time
PostgreSQL spun out of Berkeley). Inferring anything else is just
guessing, but *my* favorite theory is that it was intended to help
resolve untyped input in some long-ago implementation.
- Thomas
