Unicode Demystified

A Historical Note

Much of the terminology surrounding the presentation of Unicode in bits is relatively new, going back only a few years in Unicode's history. Indeed, some of the concepts we discuss here were originally called by different names.

When it was first designed, Unicode was a fixed-length, 16-bit standard. The abstract encoding space was 16 bits wide (a single 256 × 256 plane), and one character encoding form existed—a straightforward mapping of 16-bit code points to 16-bit unsigned integers in memory. The single official encoding scheme prefixed a special sentinel value to the front of the Unicode file to allow systems to auto-detect the underlying byte order of the system that created the file.

Early in the life of the standard, ...