MLHIM Docs Overview

Implementable semantic interoperability.

Status - Final for 2.5.0 Released: 2015-09-06

MLHIM User & Reference Manual

Use the Table of Contents on the left for navigation.

The goal of MLHIM is to be Minimalistic, Sustainable, Implementable AND Interoperable.

Press the play button to hear MLHIM pronounced.

Distribution is permitted under the terms of the Attribution-ShareAlike 4.0 International` license <>`_.


This work has received financial and in-kind support from the following persons and organizations;

  • National Institute of Science and Technology on Medicine Assisted by Scientific Computing (INpcm-MACC), coordinated by the National Laboratory of Scientific Computing (
  • Multilevel Healthcare Information Modeling Technological Development Unit, Member of the Emergent Group for Research and Innovation in Healthcare Information Technology, coordinated by Prof. Luciana Tricai Cavalini, MD, PhD (
  • Timothy W. Cook, Independent Consultant
  • Roger Erens, Independent Consultant (1.0.x version)

Error Reporting

Please report all errors in documentation and/or in the specifications of the information model as bug reports at the GitHub development site. It is easy to do and a great way to give back. See: MLHIM Issues

Purpose & Scope

Keep everything as simple as possible; but no simpler. – Albert Einstein

The purpose of the MLHIM project is to provide a free and openly available specification for implementation of computable semantic interoperability for healthcare information exchange. The MLHIM specifications are designed to provide semantic interoperability that is fully independent of any implementation specific contexts. Therefore workflow, security, user access, data persistence, etc. are all outside the scope of MLHIM.

The MLHIM site on GitHub contains a growing number of demonstration projects and tools that research how this approach and focused scope enables interoperability across many contexts. MLHIM based data can be exchanged via any transport method. Including existing HL7 v.2 and v.3 exchange systems to enhance the semantic interoperability of existing HL7 implementations.


Conformance to these specifications are represented in a Language Implementation Specification (LIS). A LIS is a formal document detailing the mappings and conventions used in relation to these specifications. A LIS is in direct conformance to these specifications when;

  1. All datatypes are defined and mapped.
  2. The value spaces of the healthcare datatypes used by the entity to be identical to the value spaces specified herein.
  3. To the extent that the entity provides operations other than movement or translation of values, define operations on the healthcare datatypes which can be derived from, or are otherwise consistent with the characterizing operations specified herein.


These specifications; * Are in indirect conformance with ISO/DIS 21090/2008. * Are in compliance with applicable sections of ISO 18308/2008. * Are in compliance with applicable sections of ISO/TR 20514:2005. * Are in compliance with applicable sections of ISO 13606-1:2007. * Are in conformance with W3C XML Schema Definition Language (XSD) 1.1


The MLHIM specifications, reference implementation and tools are available from GitHub

Previously released final versions are available, packaged as .ZIP files from Launchpad

From Release 2.4.7 on, you may download a zip file from the GitHub repository using the “Download ZIP” button. Click here to download the 2.5.0 current development version.

Official release are listed here.

The ninety and nine are with dreams, content but the hope of the world made new, is the hundredth man who is grimly bent on making those dreams come true. - Edgar Alan Poe