Code page 1163
| Company type | Code page / Character encoding |
|---|---|
| Industry | Computing / Software |
| Headquarters | Microsoft Windows environments |
| Products | Vietnamese character encoding |
Windows-1258 is a code page utilized within Microsoft Windows environments to encode Vietnamese characters, employing combining diacritical marks for tonal representation.
This encoding does not align with the Vietnamese national standard (TCVN 5712 / VSCII) nor with other frequently used encodings such as (VISCII, VNI, or VPS). Instead, it closely mirrors Windows-1252, differing primarily by excluding the s-caron and z-caron characters (which were later incorporated into Windows-1252), substituting five letters with combining diacritics to denote Vietnamese tones, replacing one character with the đồng sign, and altering eight additional characters to accommodate specific Vietnamese letters.
The adoption of combining diacritics enables Windows-1258 to represent a wide array of letter-tone combinations without compromising control characters or symbols. However, this approach necessitates that software handle conversions between precomposed characters and sequences with combining marks carefully, which adds complexity to tasks such as determining string length and performing format transformations.
IBM identifies this encoding as code page 1258 (CCSID 1258 and its extended version CCSID 5354).
In contemporary software development, UTF-8 is generally favored for Vietnamese text encoding. Due to effects related to Unicode normalization, Windows-1258 may occasionally fail to perform lossless round-trip conversions of Vietnamese Unicode data. Both Windows-1258 and Unicode place combining diacritics after the base character, similar to the approach used in VNI, but differing from that of ANSEL.
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, with an extended euro sign variant CCSID 1163) closely resembles code page 1258 but features distinct differences in certain character assignments:
| Character | Description |
|---|---|
| Alt codes 176–191 |
| Alt code | Unicode | Symbol | Notes |
|---|---|---|---|
| Alt + 176 | U+00B0 | ° | Degree sign |
| Alt + 177 | U+00B1 | ± | Plus-minus sign |
| Alt + 178 | U+00B2 | ² | Superscript two |
| Alt + 179 | U+00B3 | ³ | Superscript three |
| Alt + 180 | U+0178 | Ÿ | Latin capital letter Y with diaeresis (highlighted) |
| Alt + 181 | U+00B5 | µ | Micro sign |
| Alt + 182 | U+00B6 | ¶ | Pilcrow sign |
| Alt + 183 | U+00B7 | · | Middle dot |
| Alt + 184 | U+0152 | Π| Latin capital ligature OE (highlighted) |
| Alt + 185 | U+00B9 | ¹ | Superscript one |
| Alt + 186 | U+00BA | º | Masculine ordinal indicator |
| Alt + 187 | U+00BB | » | Right-pointing double angle quotation mark |
| Alt + 188 | U+00BC | ¼ | Vulgar fraction one quarter |
| Alt + 189 | U+00BD | ½ | Vulgar fraction one half |
| Alt + 190 | U+00BE | ¾ | Vulgar fraction three quarters |
| Alt + 191 | U+00BF | ¿ | Inverted question mark |
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