ANSI Code Page
Windows (ANSI) code pages
Microsoft defined a number of code pages known as the ANSI code pages. Don't confuse "ANSI" with "ASCII".
For function ::WideCharToMultiByte and ::MultiByteToWideChar, the first argument is code page, below MACRO represents ANSI code page:
#define CP_ACP 0 // default to ANSI code page