Getting Started

Learn how to access, download, and use the NCSL International MII Measurand Taxonomy Catalog.

What is the Measurand Taxonomy?

The NCSL International Measurement Information Infrastructure (MII) Measurand Taxonomy Catalog is a standardized, machine-readable taxonomy for describing measurement capabilities and measurands. It provides a structured way to:

  • Tag measurands in digital documents with unique, unambiguous identifiers
  • Describe laboratory calibration and measurement capabilities (CMCs) for machine consumption
  • Build digital Statements of Capability (SoAs)
  • Locate laboratories with appropriate capabilities for specific measurements
  • Enable automated CMC searches and uncertainty calculations

Each measurand is identified by a unique taxon—a hierarchical string like Measure.Temperature.Simulated.PRT or Source.Voltage.DC.

Accessing the Git Repository

The taxonomy is hosted on GitHub. You can access it in several ways:

Via Web Browser

Navigate to the repository website to browse files, view documentation, and see the commit history:

https://github.com/NCSLI-MII/measurand-taxonomy

Via Git Command Line

Clone the repository to your local machine:

git clone https://github.com/NCSLI-MII/measurand-taxonomy.git

Downloading the Taxonomy

There are several ways to download the taxonomy:

Option 1: Clone with Git (Recommended)

This gives you the full repository with history and allows you to stay updated:

git clone https://github.com/NCSLI-MII/measurand-taxonomy.git
cd measurand-taxonomy

Option 2: Download ZIP Archive

Download a snapshot of the repository as a ZIP file:

Download ZIP Archive

Option 3: Download Individual Files

The main taxonomy file is available directly:

How to Use the Taxonomy

1. Browse the Web Interface

Use this web interface to explore the taxonomy:

  • Browse — View all taxons in a searchable list
  • Disciplines — Explore by measurement discipline
  • Quantities — Browse by quantity kind
  • API — Access taxonomy data programmatically

2. Use the XML Files Directly

Parse the XML catalog in your applications:

import { parseTaxonomyXML } from './lib/xml-parser';
import fs from 'fs';

const xmlContent = fs.readFileSync('MeasurandTaxonomyCatalog.xml', 'utf-8');
const taxons = await parseTaxonomyXML(xmlContent);

3. Generate HTML Documentation

Generate human-readable HTML from the XML:

xsltproc -o MeasurandTaxonomyCatalog.html \
  MeasurandTaxonomyCatalog.xsl \
  MeasurandTaxonomyCatalog.xml

4. Use the REST API

Access taxonomy data via the REST API endpoints:

  • GET /api/taxons — List taxons (active only by default)
  • GET /api/taxons/[name] — Get a specific taxon
  • GET /api/disciplines — List disciplines
  • GET /api/search?q=... — Search taxons
  • GET /api/openapi — OpenAPI contract

See the API documentation for full details.

What Should the Taxonomy Be Used For?

The Measurand Taxonomy is designed for machine-readable measurement specifications and should be used for:

Digital CMCs (Calibration and Measurement Capabilities)

Describe laboratory services unambiguously for machine consumption. Each CMC comprises a measurand specification (using a taxon) together with measurement uncertainty.

Digital Instrument Specifications

Tag measuring instruments with their measurand capabilities using standardized taxons, enabling automated matching between instruments and calibration services.

Statements of Capability (SoAs)

Build machine-readable SoAs that laboratories can use to communicate their capabilities, and customers can use to search for appropriate calibration services.

Digital Calibration Certificates

Reference measurands in calibration certificates using standardized taxons, ensuring consistency and enabling automated processing.

Automated CMC Searches

Enable software to automatically search for laboratories with appropriate capabilities based on measurand taxons, measurement ranges, and uncertainty requirements.

Important: Taxons are used for internal document encoding and machine processing. For human-readable documents, use aliases or generate readable text from the taxon definitions.

Additional Resources