Code page 1129
| Company type | Code page / Character encoding |
|---|---|
| Industry | Computing / Text encoding |
| Products | Vietnamese text encoding using combining diacritics |
| Parent | Windows-1252 (based on) |
Windows-1258 is a code page implemented in Microsoft Windows to encode Vietnamese text, employing combining diacritical marks for tonal representation.
This encoding is not compatible with the Vietnamese national standard (TCVN 5712 / VSCII) or other widely used encodings such as VISCII, VNI, and VPS. Instead, Windows-1258 is largely based on Windows-1252, but it excludes the s-caron and z-caron characters (which were later additions to Windows-1252), replaces five letters with combining diacritics to represent Vietnamese tones, substitutes one character with the đồng sign, and alters eight additional characters to accommodate unique Vietnamese letters.
By utilizing combining diacritics, this code page supports numerous combinations of base letters and tone marks without sacrificing control characters or symbols. However, this approach necessitates sophisticated software handling for accurate conversion between precomposed characters and sequences of base letters plus combining marks. It also introduces complexity when calculating the length of visible strings.
IBM identifies Windows-1258 as code page 1258 (also known as CCSID 1258 and its euro-extended variant CCSID 5354).
Although Windows-1258 can encode Vietnamese text, contemporary software predominantly uses UTF-8, since Windows-1258 may fail to perform reliable round-trip transformations to Unicode due to issues with Unicode normalization. Both Windows-1258 and Unicode place combining diacritics after the base character.
Character set
The following table presents the characters defined in Windows-1258 alongside their corresponding Unicode code points.
...
Code page 1129
IBM's code page 1129 (identified as CCSID 1129 and its euro sign extended form CCSID 1163) closely resembles code page 1258 but features particular distinctions outlined in the table below:
| Code Range | Characters |
|---|---|
| Bx | |
| Alt Codes 176–191 | |
| Includes symbols such as degree sign, plus-minus, superscripts, micro sign, pilcrow, middle dot, ligatures, ordinal indicators, angle quotation marks, and fractions. Some differ from Windows-1258 (highlighted). |
- FFD = Differences compared to Windows-1258