HUTN is an OMG standard for storing models in a human understandable format. In a sense it is a human-oriented alternative to XMI; it has a C-like style which uses curly braces instead of the verbose XML start and end-element tags. Epsilon provides an implementation of HUTN which has been realized using ETL for model-to-model transformation, EGL for generating model-to-text transformations, and EVL for checking the consistency of HUTN models.
The OMG provides a complete specification of the HUTN syntax.