This document describes the serialization of the lexical markup framework (LMF) model defined as an extensible markup language (XML) model derived from the language base exchange (LBX) schema and compliant with the W3C XML schema. This serialization covers the classes, data categories, and mechanisms of ISO 24613‑1 (core model), ISO 24613‑2 (machine-readable dictionary (MRD) model), and ISO 24613‑3 (etymological extension).