IVOA UCD1+ Documentation

This page gives access to the documents related to UCD1+ definition. The reference document on UCD1+ is maintained on the IVOA web pages.
If you have never heard of UCD, their origin and objectives are summarized here. The no longer maintained UCD1 version is still accessible.

List of valid words for UCD1+

Latest list of valid words for UCD1+ : ucd1p-words.txt (links to ucd1p-words-20070402.txt)
Explanations on the vocabulary are available on the IVOA web site

The first character on each line is a flag indicating if the word can be used as a primary word (P), or not (secondary - S), or both (Q).
(E) and (C) can be followed by respectively 1 and 2 words describing portions of the electromagnetic spectrum. (V) means vector, and can be followed by a word describing the axis or reference frame in which the measure is done. Each UCD1+ word is followed by its explanation.

The history of changes, and previous lists are given below:

ucd1p-words-20070402.txt - IVOA Recommendation v1.23
ucd1p-words-20051231.txt - IVOA Recommendation v1.11
ucd1p-words-20050712.txt - See UCDlist-20050712.pdf (PR) for changes
ucd1p-words-20050429.txt - See WD-UCDlist-20050429.pdf for changes
ucd1p-words-20040823.txt - See WD-UCDlist-20040823.pdf for changes
ucd1p-words-20040520.txt removal of src.veloc.orbit, addition of em.gamma.soft and em.X-ray.hard, renaming of em.X-ray.med to em.X-ray.medium.
ucd1p-words-20040426.txt - first release
ucd1p-words-20040217.txt - preliminary release, no definitions yet

Comments, feedback, suggestions

A feedback form is available online to suggest the creation of new UCD.

UCD tools

UCD tree browser: available in Java and Javascript
Try the UCD builder to build relevant UCD.
Various simple tools to translate, explain, validate, upgrade, assign UCD1+. Also available as Web Services.
This tool can find UCD from keywords, but is less powerful...

Application to VizieR

Results of the application of the new scheme to VizieR are given below:

Correspondence between UCD1 and UCD1+ (updated 2005/05/11) : for each UCD1 used in VizieR, the equivalent UCD1+ is given.

Old UCD material

Documents and tool related to UCD1 are no longer maintained. You can however still access them here.