What does the "503 day" refer to?


In multiple fanarts and fanfic websites of Full Metal Alchemist, I have seen
mentions of the "503 day". Here's an example:

[![Edward & Winry
503](https://i.stack.imgur.com/9X4VNm.jpg)](https://i.stack.imgur.com/9X4VNm.jpg)

I did read and watch Full Metal Alchemist and Full Metal Alchemist Brotherhood
and I do not remember any mention of such a date. It does not match with the
date Ed engraved into his State Alchemist Pocket Watch either.

What does the "503 day" refer to?




503 day is supposed to be the 3rd of May (5/03), which is the Edward x Winry
day, or Edwin day in short.

There are two reasons for this coming into existence.

First, there's a jeans brand called Edwin and one of their logos contains the
number 503.

[![enter image description
here](https://i.stack.imgur.com/eAZNy.jpg)](https://i.stack.imgur.com/eAZNy.jpg)

Second, when Winry goes to Central City she's in room 503 of the hotel.




503 day is supposed to be the 3rd of May (5/03), which is the Edward x Winry
day, or Edwin day in short.

There are two reasons for this coming into existence.

First, there's a jeans brand called Edwin and one of their logos contains the
number 503.

[![enter image description
here](https://i.stack.imgur.com/eAZNy.jpg)](https://i.stack.imgur.com/eAZNy.jpg)

Second, when Winry goes to Central City she's in room 503 of the hotel.

