Earlier versions of Windows provided a variety of functions to support conversions between and within the ANSI and OEM character sets. Examples include the AnsiUpper, AnsiLower, AnsiUpperBuff, and AnsiLowerBuff functions for conversion within the ANSI character set; the AnsiToOem, AnsiToOemBuff, OemToAnsi, and OemToAnsiBuff functions for conversions between the ANSI and OEM character formats; and the AnsiNext and AnsiPrev functions provided for string-scanning operations.
In most cases, even though these functions are technically obsolete, newer versions of Windows supply backward compatibility in the form of macros that call the newer function versions. For example, the old AnsiUpper function is now implemented as a macro invoking the new CharUpper API function. In like fashion, AnsiNext now invokes CharNext, and AnsiToOem invokes the CharToOem API function.
Functionally, each of these operations remains essentially the same as in the earlier Windows version. The singularly important difference is that they are now Unicode-compatible, not just ANSI-compatible.