Reference to 31.10.1 The Diary File
It provides example as
April 15, 2020 Income tax due.
M-x calendar to the date of Apr 15, 2020 and strike d, it prompts a buffer as
2020-04-15 Wednesday ===================== ISO date: Day 3 of week 16 of 2020 Last Quarter Moon 7:01am (CST) Sunrise 5:23am Sunset 6:30pm 2020 Income tax due.
It seems to work properly, but if I check the date of Apr 15, 2021
2021-04-15 Thurday ===================== ISO date: Day 4 of week 15 of 2021 Sunrise 5:24am Sunset 6:29pm 2020 Income tax due.
The "Income tax due" appeared again and it actually displayed every year on the date Apr 15.
What's the problem?
Org mode version 9.4 in Emacs 26.3 with Ubuntu 19.10