Ann: Renounceable Issue, page-149

Not quite - the record date and ex-date are different. 4th is when shares start trading excluding rights - the ex date. This is because a share bought on the 4th settles on the 6th, after the record date of end of business 5th April.
Buy on the 1st, settle two business days later on the 5th. Eligible for rights.

But yes, it's a very short timetable and has obviously not given enough time for people to clearly understand it, hence the bizarre trading on the NZX yesterday. Shares rose to a peak of ~40% of the implied price on Friday, corrected for the rights price, and closed nearly 20% up. The NZX reference price screw-up means they were reporting it as a big down day, causing further confusion.