UTF16like

UTF16like is a hypothetical character encoding family designed to resemble the UTF-16 encoding used for Unicode text. It uses 16-bit code units and represents most characters with a single code unit in the Basic Multilingual Plane, while supplementary characters (U+10000–U+10FFFF) are encoded with a pair of 16-bit units known as surrogates. The high-surrogate range is U+D800–UDBFF and the low-surrogate range is U+DC00–U+DFFF. Unpaired surrogates are treated as encoding errors by decoders.

Endianness in UTF16like follows the same pattern as UTF-16: data can be stored in big-endian or little-endian order. A byte order mark at the start of a text stream or file, or an explicit endianness convention, is used to indicate byte order. This affects how code units are serialized and parsed.

Compatibility and conversion: UTF16like is designed to interoperate with systems that operate on 16-bit units. It can be converted to and from UTF-8 or UTF-32, with decoding and encoding processes responsible for constructing or decomposing surrogate pairs. Normalization and combining marks are handled at the code point level, independent of the underlying encoding.

Advantages and challenges: The encoding provides straightforward indexing by code units and efficient storage for BMP characters, but surrogate handling adds complexity for supplementary planes. Correctly managing endianness, detecting unpaired surrogates, and ensuring portable cross-platform handling are common challenges.

Applications: UTF16like is primarily used as a conceptual or educational model to illustrate how 16-bit Unicode encodings operate and to discuss interoperability scenarios. It is not an official standard. See also Unicode, UTF-16, surrogate pairs.