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 The no longer maintained UCD1 version is still accessible.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 IVOA 1.3 REC ucd1p-words-20180527.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:

Comments, feedback, suggestions

As per the procedure defined for modifications to the UCD vocabulary, a Request For Modification (RFM) wiki page is used to discuss changes to the list.
You can also send an email to the semantics@ivoa.net mailing list, or contact directly the UCD scientific board.

UCD tools

Application to VizieR

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

Old UCD material

Documents and tool related to UCD1 are no longer maintained.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