Unicode 5.1.0 contains over 100,000 characters, and provides significant additions and improvements that extend text processing for software worldwide. Some of the key features are: increased security in data exchange, significant character additions for Indic and South East Asian scripts, expanded identifier specifications for Indic and Arabic scripts, improvements in the processing of Tamil and other Indic scripts, linebreaking conformance relaxation for HTML and other protocols, strengthened normalization stability, new case pair stability, plus others given below.

In addition to updated existing files, implementers will find new test data files (for example, for linebreaking) and new XML data files that encapsulate all of the Unicode character properties.

A major feature of Unicode 5.1.0 is the enabling of ideographic variation sequences. These sequences allow standardized representation of glyphic variants needed for Japanese, Chinese, and Korean text. The first registered collection, from Adobe Systems, is now available at http://www.unicode.org/ivd/.

Unicode 5.1.0 contains significant changes to properties and behaviorial specifications. Several important property definitions were extended, improving linebreaking for Polish and Portuguese hyphenation. The Unicode Text Segmentation Algorithms, covering sentences, words, and characters, were greatly enhanced to improve the processing of Tamil and other Indic languages. The Unicode Normalization Algorithm now defines stabilized strings and provides guidelines for buffering. Standardized named sequences are added for Lithuanian, and provisional named sequences for Tamil.

Unicode 5.1.0 adds 1,624 newly encoded characters. These additions include characters required for Malayalam and Myanmar and important individual characters such as Latin capital sharp s for German. Version 5.1 extends support for languages in Africa, India, Indonesia, Myanmar, and Vietnam, with the addition of the Cham, Lepcha, Ol Chiki, Rejang, Saurashtra, Sundanese, and Vai scripts. Scholarly support includes important editorial punctuation marks, as well as the Carian, Lycian, and Lydian scripts, and the Phaistos disc symbols. Other new symbol sets include dominoes, Mahjong, dictionary punctuation marks, and math additions. This latest version of the Unicode Standard has exactly the same character assignments as ISO/IEC 10646:2003 plus Amendments 1 through 4.