Unicode Support
InterSystems IRIS supports the Unicode international character set. Unicode characters are 16-bit characters, also known as wide characters.
The $ZVERSION special variable (Build nnnU) and the $SYSTEM.Version.IsUnicode()Opens in a new tab method show that the InterSystems IRIS installation supports Unicode.
For most purposes, InterSystems IRIS only supports the Unicode Basic Multilingual Plane (hex 0000 through FFFF) which contains the most commonly-used international characters. Internally, InterSystems IRIS uses the UCS-2 encoding, which for the Basic Multilingual Plane, is the same as UTF-16. You can work with characters that are not in the Unicode Basic Multilingual Plane by using $WCHAR, $WISWIDE, and related functions.
InterSystems IRIS encodes Unicode strings into memory by allocating 16 bits (two bytes) per character, as is standard with UTF-16 encodings. However, when saving a Unicode string to a global, if all characters have numerical values of 255 or lower, InterSystems IRIS stores the string using 8 bits (one byte) per character. If the string contains characters with numerical values greater than 255, InterSystems IRIS applies a compression algorithm to reduce the amount of space the string takes up in storage.
Conversions of Data
For conversion between Unicode and UTF-8, and conversions to other character encodings, refer to the $ZCONVERT function. You can use ZZDUMP to display the hexadecimal encoding for a string of characters. You can use $CHAR to specify a character (or string of characters) by its decimal (base 10) encoding. You can use $ZHEX to convert a hexadecimal number to a decimal number, or a decimal number to a hexadecimal number.
Unicode in Identifiers
Unicode letters are alphabetic characters with decimal character code values higher than 255. For example, the Greek lowercase lambda is $CHAR(955), a Unicode letter.
Unicode letters are permitted in identifiers, with the following exceptions:
-
Variable names: local variable names can contain Unicode letters. However, global variable names and process-private global names cannot contain Unicode letters. Subscripts for variables of all types can be specified with Unicode characters.
-
Administrator user names and passwords used for database encryption cannot contain Unicode characters.
The Japanese locale does not support accented Latin letter characters in InterSystems IRIS names. Japanese names may contain (in addition to Japanese characters) the Latin letter characters A-Z and a-z (65–90 and 97–122), and the Greek capital letter characters (913–929 and 931–937).
