The X license is a free software license that is compatible with the GNU GPL license( see http://www.gnu.org/philosophy/license-list.html#GP LCompatibleLicenses>http://www.gnu.org/philosophy/l icense-list.html#GPLCompatibleLicenses). The text of the X license is available at http://www.x.org/terms.htm.
The license change is effective starting with release 1.8.1 of ICU4C and release 1.3.1 of ICU4J. These are update releases of ICU that add very substantial performance improvements over the previous versions, especially when determining the sort order for text in different languages.
About ICU (International Components for Unicode)
ICU provides provides robust and full-featured Unicode support on a wide variety of platforms, both in C/C++ and in Java. The C/C++ libraries (ICU4C) are designed to have the same features and overall architecture as the Java version (ICU4J) for compatibility across both platforms and programming languages. ICU offers a full multi-threading model and a flexible locale model. Unlike the standard C model for internationalization, programs using ICU can get precisely the same results on each platform - even platforms running EBCDIC natively. ICU also offers JNI interfaces (ICU4JNI) for collation and character conversion, so that Java programs can take advantage of much faster performance than Standard Java for these important functions.
ICU supports a large number of countries, countries with different calendar systems, different ways to format dates, times, and numbers, different timezones, different character sets, different writing directions, and different sorting order. ICU provides full-featured character code conversion, crucial for correctly interpreting the wide variety of encodings used in HTML, XML, email, and on the many platforms ICU supports. It includes support for the new Chinese Standard, GB 18030. ICU has fast, efficient text comparison, which is compliant with the Unicode Collation Algorithm and ISO 14651 - yet takes about half the storage in database indexes compared to other implementations. ICU's layout manager determines the precise location and shapes for characters from English, Arabic, Hebrew, Hindi, and other scripts.