\subsection{Full utype serialisation} 

In this approach,  relational views of the TimeSeries described above are provided. Hierarchies of classes showing 1 to 1 relationships are grouped in one single table. Table x shows the list of tables used to map the model with the full set of their columns metadata ( utype, datatype, ucd, unit and xtype), in the case of example 1.
The VODataservice "tableset" representation of this set of tables is described in Appendix. 

Each TimeSeries project as its own subset of attributes of the generic model. This leads to a specific partial relational view of the model. For each of these a dedicated table like table x could be provided. See the tableset representations in Appendix. 

The structure is made of 4 "tables" number which seems to be a compromise to separate very differents groups of classes without having too much of them.

The main "table" is the data table where the actual values of the independant variable (Time stamps) and of the "one to many" varying variables are stored.

The three other tables, which we can call "generic TimeSeries metadata" tables gathers respectively :

\begin{itemize}
\item Dataset, curation and dataid classes attributes. This is directly derived from similar concepts in ObsCore and Dataset metadata model. 
\item Characterization describes where and how the dataset is situated in the physical parameter space; most of the columns there should be redondant with what is in Obscore Char.
\item Coordsys table. This table mainly serializes stc and gathers the coordinate frames (time, space, spectral) used in the TimeSeries as well as the different photometric filter descriptions, assimilated to "flux frames".  
\end{itemize}

Utypes are built by concatenating class and attributes names following a path from a top element to the actual considered leave. They don't designate a class atrribute per se but a role of the attribute value with respet to the full model.

Table x and its vodaitaservice tableset expressions  are an absolute reference for the utypes definition and should be reproduced in the timeSeries model specification.

"Tables" mentionned here and described in the Appendix are not required to be serialized as TABLE elements in VOTable. In the case there is only one single TimeSeries in the VOTable document, "generic metadata tables" have only one single instance. They can be serialized as groups and their columns as PARAMS instead of using TABLES with one single row.

The Appendix illustrates the background of the  examples the serialization of which is provided at the  URL included here, starting with the simplest example : \\ 
\begin{small}
http://volute.g-vo.org/svn/trunk/projects/time-domain/time-series/standardized\_votables/\\
/francois/SDSS\_J080434.20+510349.2\_VizieR\_complete\_utypes.xml \\
\end{small}
This TimeSeries is a light curve for a single SDSS object and is provided as full Catalog in VizieR. It has one single dependant variable : V magnitude.

Obviously most of the  use cases will be more complex, 
as in the two following examples

Example 2 
 is an excerpt of table 3 of the VizieR catalog provided by Shenavrin and coworkers in 2011 (Shenavrin et al, Astronomicheskii Zhurnal, 2011, Vol. 88, No. 1, pp. 34-85.) where the rows present a basic time with a Time Shift for each photometric band.
 It presents a main time as independant variable and several magnitudes in different  bands for the same individual exposure. The exact measurement time is slightly varying according to the band (due to a shift of time for changing the filter) in such a way that several secondary times are given for each main TimeStamp as well.\\ 
\begin{small}
(http://volute.g-vo.org/svn/trunk/projects/time-domain/time-series/standardized\_votables/\\
francois/BetaLyr\_Vizier\_complete\_utypes.xml) \\
\end{small}


In example 3 where exoplanet data are provided (GAPS project) some columns provide flux or radial velocity measurements which have a specific utype in an IVOA model (stc or phot). Some other don't have because the definition of the quantity is outside the scope of STC or photometric datamodel. In that case a generic "measurement" utype (ts:TimeSeriesData.NDPoint.dependantObservedObject.CoordMeasure.coord) is given and the flavor can be precised with help of the ucd.
In some other cases the column contains an error on some of these measurements. In that case the utype is set to :
"

\begin{small}
(http://volute.g-vo.org/svn/trunk/projects/time-domain/time-series/standardized\_votables/\\
francois/GAPS\_kp7\_complete\_utypes.xml) \\
\end{small}

 
In example 4, extracted from Gaia DR2 catalog, the TimeSeries is a concatenation of three set of NDpoints, one per each photomteric band

\begin{small}
(http://volute.g-vo.org/svn/trunk/projects/time-domain/time-series/standardized\_votables/\\
francois/GaiaSample3Tables\_complete\_utypes.vot) \\
\end{small}


In example 5, the Gaia DR2 TimeSeries with its three bands is organized in a single table.


\begin{small}
(http://volute.g-vo.org/svn/trunk/projects/time-domain/time-series/standardized\_votables/\\
francois/GaiaDR2Example-time-series.xml) \\
\end{small}


