CodePage 0 is CP_ACP, the default Ansi CodePage on a system, you can change it without reinstalling Windows

You might think the below question on CodePage zero is Delphi related, but most of it is not.

It is about CP_ACP (the currently Active CodePage, and has some interesting observations:

• It can vary accross systems
• It can be changed without reinstalling Windows
• Delphi 2009 sometimes did a bad job with it (but Delphi 2010 and up are OK)

CP_ACP is the major reason people have difficulties exchanging the data in text files between applications on different computers.

Oh and you can get the actual value of the active Active CodePage using GetACP, but CP_ACP isn’t always slower..

–jeroen

via: delphi – What is Codepage 0? – Stack Overflow.