UCD validator

Tue Mar 1 17:34:18 CET 2022

Dear Bo, dear Alberto,

the tool you are using for validation does not handle properly 
contatenation for 3 terms especially as you describe when two SS need to 
be concatenated.

we use instead this assigning tool now :
http://cds.u-strasbg.fr/UCD/cgi-bin/descr2ucd

from the definition :  "luminosity in V band min value"
it builds : /phys.luminosity;em.opt.V;stat.min/

if you want to validate your ucd fields, I think the stilts tool from 
Mark Taylor will help a lot
http://www.star.bristol.ac.uk/~mbt/stilts/sun256/votlint-usage.html

here attached is a test votable :
when you install stilts and run this command :
/>> stilts -verbose votlint ucd=true validate=true votable=./testucd.xml
you get this result
/INFO: votlint version=null validate=true ucd=true unit=null maxrepeat=4 
votable=./testucd.xml out=-
ERROR (l.22, c.97): Bad UCD "em.opt.V;phys.luminosity;stat.min" 
(BAD_SEQUENCE): UCD starting with a SECONDARY UCD word: "em.opt.V"! Such 
words can NOT be in first position.

so the 2 SS combinations are valid and only em.opt  is detected in the 
wrong position , which is correct.

I encourage you to use votlint for your checks.

best , Mireille

Le 25/02/2022 à 16:59, Bo Milvang-Jensen a écrit :
>
> Dear Alberto and all,
>
> Thank you for adding me in cc. I am the user who is working on 
> assigning UCDs to 1200 catalogue columns, prior to publication in 
> ESO's Phase 3 system (supported by Laura Mascetti), and that is a bit 
> of a headache. Just to spell out this particular problem: the UCD1+ 
> v1.4 document only says (in my reading) that an S word cannot be 
> first, it does not say that an S word has to be last! but the 
> validator at CDS seems to think so.
>
> This means that according to the validator at CDS there is no way to 
> construct a UCD describing a minimum value of a V-band luminosity, as 
> the corresponding 3 words cannot be combined in any way:
>
> phys.luminosity;stat.min;em.opt.V --- violates the claimed ESS rule
> phys.luminosity;em.opt.V;stat.min --- violates the claimed ESS rule
> stat.min;phys.luminosity;em.opt.V --- of course not allowed (stat.min: 
> S word)
>
> The validator will also complain about the sequences QSS and PSS.
>
> PS: I have a couple of other questions/problems with the UCD standard 
> that I would like to ask/report. What is the best channel?
>
> Kind regards, Bo
>
> On 2/25/22 4:31 PM, Alberto Micol wrote:
>>
>> Dear CDS and UCD editors,
>>
>> I'd like to follow up on two original inquiries of mine, both sent 
>> 21.02.2020, attached below,
>>
>> and ask two questions.
>>
>> We currently have an inquiry from one of our ESO principal 
>> investigators (in cc),
>>
>> who needs to identify the correct UCDs needed to publish a catalog,
>>
>> and his inquiry is exactly on the same issue, the CDS validator, 
>> published at:
>>
>> http://cdsweb.u-strasbg.fr/UCD/tools.htx
>>
>> Using your "validate" form in that page on the following UCD:
>>
>> phot.flux;em.radio;arith.ratio
>>
>> one gest the error:
>>
>> 8 **** invalid sequence of syntax codes (ESS)
>>
>> Same result for BO's UCD:
>>
>> phys.luminosity;stat.min;em.opt.V
>>
>> 8 **** invalid sequence of syntax codes (ESS)
>>
>> And similar result for my UCD (see first attachment):
>>
>> phot.flux.density;em.wl;stat.uncalib;src.net
>>
>> where I get:
>>
>> 8 **** invalid sequence of syntax codes (EQSS)
>>
>> But if I remove any of the two "S" words, than I no longer get an error,
>>
>> despite the fact that a EQS should be equivalent to an ESS, given 
>> that Q can be either a P or an S.
>>
>> So, it seems to me that your validator does not accept 2 "S" words in 
>> a UCD.
>>
>> Please note that I took that first UCD above 
>> (phot.flux;em.radio;arith.ratio)
>>
>> from a list of examples of *legal UCDs* in the UCD standard itself:
>>
>> see 
>> https://www.ivoa.net/documents/REC/UCD/UCD-20050812.html#toc-header-10
>>
>> So, that must be a valid UCD.
>>
>> *Q1: Could you please verify the logic of the validator, also 
>> considering what follows?*
>>
>> Before concluding, let me add a potential explanation of this issue…
>>
>> Probably this is the result of a statement in the IVOA endorsed note, 
>> par. D2, at:
>>
>> https://www.ivoa.net/documents/UCD1+/20210616/EN-UCDlist-1.4-20210616.html#tth_sEcD.2
>>
>> which states that:
>>
>> "P, S and Q are the labels expressing in which position of a UCD 
>> expression a term can be used,
>>
>> P in first place, S as suffix, and Q in both allowed position: head 
>> and tail.
>>
>> "
>>
>> The word "tail" is probably taken literally by your validator, 
>> resulting in this 2 "S" words-error.
>>
>> But it is that endorsed note that uses "tail" in a wrong way,
>>
>> as explained in my second attachment (see therein: "contradiction 
>> with the sentence in B").
>>
>> *Q2: I'd like to ask the UCD editors to please consider my suggested 
>> amendment to the standard (see second attachment),*
>>
>> *So to avoid any possible confusion on the word "tail".*
>>
>> Many thanks, and sorry for the long email,
>>
>> Alberto
>>
>> *From: *Alberto Micol <amicol at eso.org>
>> *Date: *Friday, 21. February 2020 at 10:12
>> *To: *CDS question <cds-question at unistra.fr>
>> *Cc: *Laura Mascetti <lmascett at partner.eso.org>, Baptiste Cecconi 
>> <baptiste.cecconi at obspm.fr>
>> *Subject: *UCD validator
>>
>> Using the UCD validator service:
>>
>> http://cds.u-strasbg.fr/UCD/cgi-bin/WS_validate
>>
>> on the following ucd1+:
>>
>> phot.flux.density;em.wl;stat.uncalib;src.net
>>
>> I get the following error:
>>
>> 8 **** invalid sequence of syntax codes (EQSS)
>>
>> It is unclear to me what the problem is, as the  em.wl (Q) is 
>> immediately following the photometric part (E),
>>
>> and the two secondary (S) tokens are indeed at the end of the ucd.
>>
>> Could you let me know what the problem is, and then maybe modify the 
>> validator to provide a more explanatory text,
>>
>> as it does, for example, when inputting:
>>
>> phot.flux.density;stat.uncalib;src.net;em.wl
>>
>> whose error is clearly telling the user what to repair:
>>
>> 8 **** invalid sequence of syntax codes (ESSQ) S word must be last
>>
>> Many thanks,
>>
>> Alberto
>>
>> PS: I understand that the UCD standard gives contradictory 
>> information regarding the Q tokens, I will write to Baptiste to 
>> clarify that.
>>
>> *From: *Alberto Micol <amicol at eso.org>
>> *Date: *Friday, 21. February 2020 at 10:36
>> *To: *Baptiste Cecconi <baptiste.cecconi at obspm.fr>
>> *Cc: *Laura Mascetti <lmascett at partner.eso.org>
>> *Subject: *UCD1+: some confusion on the "Q" tokens
>>
>> Ciao Baptiste,
>>
>> I'd like to highlight to you a (slight) inconsistency in the UCD1+ 
>> standard (v1.3), but also repeated in the current Proposed Endorsed 
>> Note 2020-02-12v1.4.
>>
>> In: A.2 P or S syntax code: Which is the most pertinent position for 
>> a UCD word?
>>
>> /P, S and Q are the labels expressing in which position of a UCD 
>> expression a term can be used, P in first place, S as suffix, and Q 
>> in both allowed position: head and tail. /
>>
>> The issue I have is with "… in both allowed position(s): head and 
>> tail", which seems to indicate that a Q term
>>
>> can either be first or last, but not in the middle of a longer ucd, 
>> and this would be in contradiction with the sentence in B:
>>
>> B List of valid words
>>
>>  3. /“Q” means that the word can be used indifferently as first or
>>     secondary word; /
>>
>> Can I suggest to modify that sentence in A2, as follows:
>>
>> /P, S and Q are the labels expressing in which position of a UCD 
>> expression a term can be used, P in first place, S as suffix, and Q 
>> //either as P or S./
>>
>> ?
>>
>> Many thanks,
>>
>> Alberto
>>

-- 
--
Mireille Louys,  MCF (Associate Professor)
Centre de données CDS		IPSEO, Images, Laboratoire Icube
Observatoire de Strasbourg	Telecom Physique Strasbourg
11 rue de l'Université		300, Bd Sebastien Brandt CS 10413
F- 67000-STRASBOURG		F-67412 ILLKIRCH Cedex
Tel: +33 3 68 85 24 34
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