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Hello DAL members,
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<div class="">I would like to bring to your attention an issue related to service descriptor input parameters in the DataLink (<a href="https://www.ivoa.net/documents/DataLink/20211115/WD-DataLink-1.1-20211115.html#tth_sEc4.3" class="">https://www.ivoa.net/documents/DataLink/20211115/WD-DataLink-1.1-20211115.html#tth_sEc4.3</a>).
The problem that I’ve run into relates to the fact that the syntax of `MIN` and `MAX` for those parameters is not explicit. </div>
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<div class="">The example in that document (<a href="https://www.ivoa.net/documents/DataLink/20211115/WD-DataLink-1.1-20211115.html#tth_sEc4.7" class="">https://www.ivoa.net/documents/DataLink/20211115/WD-DataLink-1.1-20211115.html#tth_sEc4.7</a>) as:</div>
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<pre xmlns="http://www.w3.org/1999/xhtml" style="margin-left: 2em; counter-reset: pre_line 0;" class=""><span class="verbline" style="counter-increment: pre_line 1;"><PARAM arraysize="2" datatype="double" name="BAND"
</span><span class="verbline" style="counter-increment: pre_line 1;"> ucd="em.wl" unit="m" value=""
</span><span class="verbline" style="counter-increment: pre_line 1;"> xtype="interval">
</span><span class="verbline" style="counter-increment: pre_line 1;"> <DESCRIPTION>Spectral cutout interval</DESCRIPTION>
</span><span class="verbline" style="counter-increment: pre_line 1;"> <VALUES>
</span><span class="verbline" style="counter-increment: pre_line 1;"> <MIN value="3.52631986e-07"/>
</span><span class="verbline" style="counter-increment: pre_line 1;"> <MAX value="9.21500998e-07"/>
</span><span class="verbline" style="counter-increment: pre_line 1;"> </VALUES>
</span><span class="verbline" style="counter-increment: pre_line 1;"> </PARAM></span></pre>
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<div class="">The VOTable parser in astropy does not like the syntax - it expects, and I would say logically so, that MIN and MAX have the type of the BAND param, i.e. an interval. Is there a reason not to have the above MIN and MAX expressed as the maximum
interval, i.e. <MAX value="3.52631986e-07 9.21500998e-07”/>?</div>
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<div class="">That would also be consistent with other types of PARAM. The CADC DataLink service, for example, also returns:</div>
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<div class=""><PARAM name="CIRCLE" datatype="double" arraysize="3" ucd="obs.field" unit="deg" xtype="circle" value=""></div>
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<div class=""> <MAX value="36.517259904944964 75.45304017944918 0.13160680194585758" /></div>
<div class=""> </VALUES></div>
<div class=""> </PARAM></div>
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<div class="">which VOTable parser is happy with it.</div>
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<div class="">Thank you,</div>
<div class="">Adrian</div>
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