(r2) UCDwordsRFM < IVOA

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---+ RFM (Request for modification) of the List of UCD-words

AndreaPreiteMartinez
IVOA – Semantics WG

TN - 20060713



What follows is a list of proposed requests (*RFM*) to modify/add the present standard list of ucd-words: *The UCD1+ controlled vocabulary, Vers. 1.11 - IVOA Recommendation 31 December 2005*  (http://www.ivoa.net/Documents/latest/UCDlist.html ). 

The RFMs were collected over the past few month, from suggestions coming from various members of the IVOA community. 
The list has been presented at the UCD-session in Victoria, and corrected taking into account the discussions during the meeting within the WG and with the Theory IG. Other suggestions have been added to describe attributes used by some Data Models.

The list is open for discussion in accordance with the approved standard procedure: *Maintenance of the list of UCD words, Version 1.20 - IVOA Recommendation 28 May 2006* (http://www.ivoa.net/Documents/latest/UCDlistMaintenance.html ).

Due to web security problems, for the moment we discourage the usage of the web-based form for submitting RFMs. On the other hand we can consider the present list of RFMs as a collective effort of the community, not requiring a private personal answer (see par. 2.2 and 2.3 of the maintenance document). For the time being, all the RFMs and all the corresponding answers will be grouped together in the present public document. Other RFMs could be proposed during the discussion phase, so that we can consider this document as a temporary repository of all proposed RFMs. 






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---+ A proposed new UCD1+ time-branch

---++ A more consistent approach to the description of time-related quantities with UCDs.


AndreaPreiteMartinez, IVOA – Semantics WG

---+++ TN - 20060701




The *time* branch in the IVOA Rec v1.11 is the following:


| *SF* | *word* | *description* |
| Q | time                               | Time |
| Q | time.age                           | Age |
| Q | time.crossing                      | Crossing time |
| Q | time.epoch                         | Epoch, julian date |
| Q | time.equinox                       | Equinox |
| Q | time.event                         | Duration of an event or phenomenon |
| Q | time.event.end                     | End time of event or phenomenon |
| Q | time.event.start                   | Start time of event or phenomenon |
| Q | time.expo                        | Exposure on-time, duration |
| Q | time.expo.end                      | End time of exposure |
| Q | time.expo.start                  | Start time of exposure |
| Q | time.interval                      | Interval of time |
| Q | time.lifetime                      | Lifetime |
| Q | time.obs                           | Observation on-time, duration |
| Q | time.obs.end                      | End time of observation |
| Q | time.obs.start                     | Start time of observation |
| Q | time.period                        | Period |
| Q | time.phase                         | Phase |
| Q | time.relax                         | Relaxation time |
| Q | time.resolution                    | Time resolution |
| Q | time.scale                         | Timescale |

The request is to introduce a clearer separation between *instant* of time and *duration* in time.


The situation now is:

The words referring to *instants* of time are:

time.epoch %BR%
time.event.end %BR%
time.event.start %BR%
time.expo.end %BR%
time.expo.start %BR%
time.obs.end %BR%
time.obs.start

The words referring to a *duration* or an interval of time are:

time.event %BR%
time.expo %BR%
time.obs %BR%
time.interval

(but in this last case we mean a time-bin, or the time elapsed between two events, not the duration of an event. We need to make the description clearer)

In addition we have some other rather specific time-words that we leave untouched. 


---++ Proposal: 

we keep the atoms indicating instants:%BR%
epoch, %BR%
start, %BR%
end  %BR%    
(although a strict hierarchization should give: 
epoch, epoch.start, epoch.end !!)

and we introduce a new atom  *duration*  to indicates duration, interval of time during which a generic event/observation/phenomenon is taking place.

We keep the atoms indicating what instants and duration we are referring to:%BR%
obs (observation)%BR%
expo  (exposure)%BR%
event  (generic event, pleonastic!)%BR%
and introduce a new atom 
*sequence* (to indicate a correlated sequence of observations)

One possible combination of atoms is:

*time*,   at level 1%BR%
*instants/duration*   at level 2%BR%
*type of event described*   at level 3


Examples:

| *Description* | *v1.11* | *new version* |
| time/date of observation | time.epoch | time.epoch.obs |
|  or:  | time.epoch;obs | time.epoch;obs |
| observing time | time.obs | time.duration.obs |
|   or:   | time;obs | time.duration;obs |
| exposure time | time.expo | time.duration.expo |
| start time of a sequence | time.obs.start | time.start.sequence |

In addition, we propose three more atoms to describe creation, publication/release and processing times for data, files, catalogues, etc.


The new proposed *time* branch is illustrated in the following Table. New ucd-words and new descriptions are in bold/italic. Old (v1.11) ucd-words that are not repeated in column *new version* are suppressed.



Table 1.  The proposed new *time* branch in UCD1+.








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Topic revision: r2 - 2006-07-13 - AndreaPreiteMartinez
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