Codes in Custom Formats

I find some strange codes in the listed Custom Formats. I don't think I added them. I've played with numbers with and without them and am not seeing what they do.

Anybody know where these are from and what they do?

[$-409]
[$-F800]

See also in attached .jpeg

Thank you.

Phil

It is the code assigned to the countries currency symbol.

Format Cells>>Number>>Accounting>>Symbol (Select Different Countries Currency)>>Click Custom.