The new server supports TAP-VAMDC queries using VSS1 or VSS2 languages. The query may be as simple as:
select *to retrieve the whole database, or for example
select * where (RadTransFrequency >= 9.671000e+04 and RadTransFrequency <= 9.677000e+04) and RadTransProbabilityA >= 3.000000e-06 and InChiKey in ('TXKMVPPZCYKFAC-UHFFFAOYSA-N','OKKJLVBELUTLKV-UHFFFAOYSA-N')to retrieve the S2O and CH3OH lines (InChIKey), between 96710 and 96770 MHz (RadTransFrequency), which have an Einstein coefficient above 3e-6 (RadTransProbabilityA). Once the query command is built, it is encoded in the whole HTTP url.
The list of supported restrictables (i.e. the parameters which can be used for filtering) can be found in the VAMDC documentation1. For interfacing with the command SELECT, LINEDB uses the restrictables shown in the Table 1. RadTransFrequency and RadTransProbabilityA are direct equivalent of the SELECT filters. There is no restrictable for selecting a line by its upper level energy (/ENERGY), so the filtering is performed internally in LINEDB afterwards.
The /SPECIES case is a more complex issue. LINEDB uses the molecule formula or name to identify a species. The equivalent in the XSAMS format is the OrdinaryStructuralFormula (see subsection 3.3 for details). However, because this property can be an ambiguous reference to a species (e.g. ``Methanol'' and ``CH3OH'', ``HCCCN'' and ``HC3N''), it can not be used as a filter. VAMDC offers instead the InChI (IUPAC International Chemical Identifier2) or the InChIKey (hashed InChI) as non-ambiguous identifier. In practice, LINEDB has to know how to translate the formula as an InChIKey. This is done by downloading and parsing the full Species table (and only this one) once at the beginning of the session. As of today this table provides 734 species; they are listed in the Appendix C.
SELECT option | Restrictable | Comments |
/SPECIES | InChIkey | Translation needed |
/FREQUENCY | RadTransFrequency | [MHz] |
/ENERGY | N/A | Done internally in LINEDB |
/AIJ | RadTransProbabilityA | [![]() |
/ORIGIN | (not relevant) | |
/SORTBY | (not relevant) | |
/EPSILON | (not relevant) |