Unicode

The characters “U+” are an ASCIIfied version of the MULTISET UNION “⊎” U+228E character (the U-like union symbol with a plus sign inside it), which was meant to symbolize Unicode as the union of character sets

— codepoint - Why is 'U+' used to designate a Unicode code point? - Stack Overflow

• A Programmer’s Introduction to Unicode – Nathan Reed’s coding blog

• The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) – Joel on Software

Composite and Precomposed Characters

Unicode contains a vast number of characters, many of which have different Unicode numbers, but are in fact the same character. A simple example is the letter e-acute: this can be represented by é, which in UTF-8 encoding is the two hex bytes c3 a9, or by é, which is the three hex bytes 65 cc 81. In some fonts there may be small differences, but in most cases we see identical characters and expect our computers to treat them the same.

é and é

• janlelis/uniscribe: Debug help for Unicode strings

• Precomposed character — Wikipedia

• Technical Q&A QA1235: Converting to Precomposed Unicode

• Unicode equivalence — Wikipedia

• Dark corners of Unicode / fuzzy notepad

• UAX #15: Unicode Normalization Forms

• How to normalise strings, and a new command tool to help – The Eclectic Light Company

• Apfelstrudel, Downloads – The Eclectic Light Company

Normalization forms:

• NFC: Precomposed string with canonical mapping

• NFD: Decomposed string with canonical mapping

• NFKC: Precomposed string with compatibility mapping

• NFKD: Decomposed string with compatibility mapping