Windows-1258 is a code page used in Microsoft Windows to represent Vietnamese texts. It makes use of combining diacritical marks. Windows-1258 is not compatible with VISCII. It is very similar to Windows-1252 with the differences being that s-caron and z-caron (which were added to Windows-1252 later) are missing, four of the letters with diacritics have been replaced by combining diacritics and a few other letter/diacritic combinations have been replaced.
Use of combining diacritics means that Windows-1258 can cover the large number of letter/diacritic combinations in Vietnamese without compromising coverage of control codes or symbols. However it also means that software must be careful to handle conversions between precomposed characters and combining sequences correctly when converting to/from other encodings and makes determining user-visible length of a string more difficult.
UTF-8 is the preferred encoding for Vietnamese in modern applications. Windows-1258 may not always round trip Unicode encoded Vietnamese due to Unicode normalization differences.
Code page layout
The following table shows Windows-1258. Each character is shown with its Unicode equivalent and its decimal code.
Legend: