What is the latest date you can be registered?
For example, to get approvals, set up travel, obtain visas, and so on.
In other words, if we have not yet gotten you an on-site registration
by this date, we should drop you from the waitlist. Those having the
travel flexibility required to make use of a day-before-the-conference
registration should specify a post-conference date, for example, October 15th.