The null character that terminates the string is also a two byte null character. A double-byte string differs from a multibyte string in that the characters are all a fixed length of two bytes, whereas the characters in a multibyte string are a variable length. Unicode is an example of a double-byte character set. A character in a single-byte character set that has a code point between 128 and 256. A stemming process that modifies a word's form in order to mark the grammatical subclass to which it belongs.
Subclasses are things like plural, tense and so on.
The process of making software ready to localize to any particularly locale. The software must have the superset of the capabilities for all locales, and a way of specifying which capabilities are used for any particular locale. It recognizes that multibyte characters vary in length and can jump ahead several bytes at a time. This allows it to return characters from the string one at a time, no matter how many bytes are in the characters. A language in this context refers to the linguistic rules governing a spoken human language, such as stemming, or tokenization.