Category:Attribute Conventions Dataset Discovery

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This page summarizes information related to the Attribute Convention for Dataset Discovery. (The page is a 'category' on the ESIP wiki, and provides a landing page for information on the convention and its versions.)

The Attribute Convention for Dataset Discovery identify and define a list of NetCDF global attributes recommended for describing a NetCDF dataset to discovery systems such as Digital Libraries. Software tools will use these attributes for extracting metadata from datasets, and exporting to Dublin Core, DIF, ADN, FGDC, ISO 19115 etc. metadata formats.

Current Release

The currently released ACDD document is always the one recommended for public use.

Since mid-2013, the current release is always referenced by this link:


The currently released version of the ACDD is always found at Attribute Convention for Data Discovery.

The latest working document, including new concepts and terms under consideration, can be found at Attribute Convention for Data Discovery Working.

NOTE: Occasionally the acronym UDDC (Unidata Dataset Discovery Conventions) has been used in the community to refer to this same convention. ACDD is now the preferred acronym, and Attribute Convention for Data Discovery the preferred name.

The following table describes the history of this document, including some interim versions which were not released. (In particular, the 1.2.x versions of ACDD were all unreleased working versions.)

Version/Link Released? Description Date Updated
1.0 Original Yes Original version published by Ethan Davis on the Unidata website.
(Locally saved ArchivalCopyOfVersion1.)
1.1 Previous Release Yes Attribute Convention for Data Discovery 1-1: This was the previous release of the ACDD, until updated on 1/1/2015 by version 1.3.
History: The Unidata vocabulary was migrated to the NOAA Environmental Data Management wiki on or around 2010-01-20. The discussion and developments on that page focused on mapping the ACDD elements to corresponding ISO elements. These mappings became the basis for software tools to translate from netCDF to ISO19115/19115-2/19119 (e.g. ncISO and Geonetwork.
Status: The Current Release on this site is a copy of the NOAA page, with minor modifications in the introductory text.
1.2 early beta No Attribute Convention for Data Discovery 1-2: A working draft of the 'next version' of ACDD, created 2013-04-26 and updated intermittently thereafter to follow the modifications in 1.2.3 working 2014-02-07
1.2.3 working No Attribute Convention for Data Discovery 1-2 Working: This working page was maintained as a long modification section. The Discussion page of this document contained considerable history, distilled from emails.
Also: Implemented new hierarchy of pages. Now there are permanent target pages (e.g., Attribute Convention for Data Discovery) which redirect to the Current Release (Attribute Convention for Data Discovery 1-1 and current working pages.
1.3 Current Release Yes Attribute Convention for Data Discovery 1-3: This is the latest approved release of the ACDD.
Change Summary: A summary of changes and references can be found at

Future Directions

At the moment, there is no working document per se. Instead, the Attribute Convention for Data Discovery Working link redirects to the Attribute Convention for Data Discovery Future Directions, which describes anticipated work on an object oriented '2.0' version, and also references the document used to capture issues about version 1.3.

Objectives and Goals

The ACDD is intended

  1. To allow efficient dataset discovery
  2. To allow users to use data efficiently
  3. To facilitate mapping between dataset metadata (notably netCDF) and ISO 19115.


The ACDD Steering Committee formalizes changes and additions to ACDD.

The discussion for changes to ACDD is carried out via this wiki and the ESIP Documentation Cluster mailing list. To sign up for edit privileges for this wiki you must first register at the ESIP Commons. This registration also grants access to other community resources supported by ESIP. Both the mailing list and this wiki are open and anyone in the community. ACDD will evolve based on the discussions on this list and as documented on these wiki pages. Occasionally, the discussion may need to be moderated or a decision must be made. In these cases the steering committee will vote and adopt a solution as described below.

Steering Committee

ACDD will evolve based on the direction of the steering committee, which is comprised of the following members:

  • Anna Milan (Co-chair) NGDC
  • John Graybeal (Co-chair) Graybeal.SKI Consulting
  • Dave Blodgett USGS
  • Nan Galbraith WHOI
  • Ted Habermann The HDF Group
  • Steve Hankin PMEL
  • Marcos Hermida Unidata
  • Aleksandar Jelenak The HDF Group
  • Anna Milan NGDC
  • Dave Neufeld CIRES
  • Rich Signell USGS
  • Bob Simons NMFS
  • Derrick Snowden IOOS
  • Ed Armstrong JPL

Decision Making Process

Vote 70% majority of voting members; members may decline to vote on some issues

If a vote is taken or a decision is reached, that decision should be broadcast to those who could not be present. Discussion of the decision takes place for some period of time (or till the next meeting?) If there is disagreement or ongoing discussion, the decision is not finalized. If there is no discussion or disagreement, the topic is final and will not be revisited later.

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