Eternal September or the September that never ended is Usenet slang for a period beginning in September 1993, the month that Internet service provider America Online (AOL) began offering Usenet access to its many users, overwhelming the existing culture for online forums.

Basically it returns the date as if the September 1993 never ended, for example:

<?php

echo sdate('Y-m-d', strtotime('2020-06-01'));
// echoes 1993-09-9771, e.g. the 9,771st day of September 1993

All day/month/year formats are supported, every other format is handled by the underlying date function.

Why?

Why not?