<div dir="ltr"><div><div>As has been discussed numerous times (!) in the past, JD and MJD are *not* types. For MJD values (eg Obscore t_min and t_max) one uses datatype="double" unit="d" and describes the coordinate system metadata using STC as Markus has described in a Note. The xtype attribute is to tell consumers of the votable that the value can be further parsed to turn it into a structure of some type, not further interpretted to mean something. I think that is an important distinction that is often ignored <br><br></div>I'm not sure about the high precision "days" + "seconds" double array. You need that in TAP only if you actually want to expose a single column with the multiple values, but I don't know off hand if anyone does that. (I will admit to having some double array vaulued columns in our TAP service; they are in a view called caom2.SIAv1 to support the coupleof columns in the SIAv1 output that are arrays... but they don't have xtypes). <br><br></div><div>Finally, the restriction of timestamps to a specific ISO8601 in UTC and without timezone comes from upstream of DALI -- VOResource iirc. It has been th accepted standard for years and DALI is only formalising some technical bit of it for usage in services like TAP, SIA2, etc<br><br></div>Emphasis: xtype tells the consumer how to further parse the value.<br><div><div><div><div class="gmail_extra"><br><br>-- <br><div><div dir="ltr"><div><div>Patrick Dowler<br></div>Canadian Astronomy Data Centre<br></div>Victoria, BC, Canada<br></div></div>
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