I'm not sure that describing the third Monday in February is required for the purposes of the standard under discussion, but the MARC 21 Format for Holdings Data attempts to do this for the purpose of recording and predicting publication patterns of periodicals. It's fairly inscrutable and I wouldn't necessarily recommend it for this standard. It can be found at http://www.loc.gov/marc/holdings/hd853855.html under subfield $y. The third Monday in February would be described as w0203mo. ------------------------------------------ John Hostage Authorities and Database Integrity Librarian Langdell Hall Harvard Law School Library Cambridge, MA 02138 [log in to unmask] +(1)(617) 495-3974 (voice) +(1)(617) 496-4409 (fax) http://www.law.harvard.edu/library/ -----Original Message----- From: Discussion of the Developing Date/Time Standards [mailto:[log in to unmask]] On Behalf Of Ray Denenberg, Library of Congress Sent: Monday, February 28, 2011 11:41 To: [log in to unmask] Subject: Re: Requirements // Ordinal and Week dates Once again I ask for an explanation of the requirement. I have two areas of confusion. First, the recent examples include, for example, "3rd Monday in Feb. 2011". Is this a real example? The third Monday in February of 2011 is a real date and can be represented as "2011-02-21". I had thought that you wanted to represent "third Monday in February", independent of year, in order to represent a pattern, as in this case a particular US holiday, i.e. George Washington's Birthday, falls each year on the third Monday in February. Second (as Bruce has already asked) assuming you want to represrent "third Monday in February" why can't it be represented as the human readable string 'third Monday in February', or '3rd Mon. in Feb'; i.e. why does it need to be normalized for computer readability? Can you provide a use case where machine readability is necessary? Ray