XMLn

XMLn (pronounced "XML-enn") is a compact variant and serialization concept related to the Extensible Markup Language (XML). It was proposed as a way to reduce verbosity and parsing overhead by replacing repeated tag names with numeric identifiers or shortened token forms while retaining a clear mapping to standard XML document structures.

The core idea behind XMLn is to separate the semantic names used by developers from the on-wire representation used for storage or transport. Documents encoded in XMLn typically include a lightweight dictionary mapping numeric or short tokens to full element and attribute names, enabling smaller file sizes and faster parsing in constrained environments. XMLn can be expressed in both text and binary forms; the binary variants focus on minimizing byte-level overhead for network transmission and embedded systems.

Advocates highlight benefits such as reduced bandwidth usage, improved parsing performance, and easier integration with constrained devices (for example, some IoT scenarios). Critics point to reduced human readability, higher tooling complexity, and potential interoperability challenges compared with plain XML and other compact formats like JSON or established binary XML standards.

Interoperability with XML is usually achieved through converters that rehydrate XMLn back into standard XML and vice versa. Adoption tends to be niche, driven by specific performance or size constraints rather than general-purpose document interchange.