  The theory interest group in the International Virtual Observatory Alliance
(IVOA) has the goal of ensuring that theoretical data and services are taken
into account in the IVOA standards process. In this poster we present some of
the efforts carried out by this group to include evolutionary synthesis models
in the VO framework. In particular we present the VO tool PGos3, developed by
the INAOE (Mexico) and the Spanish Virtual Observatory which includes most of
public SSP models in the VO framework (e.g. VOSpec). We also describe the
problems related with the inclusion of synthesis models in the VO framework and
we try to encourage people to define the way in which synthesis models should
be described. This issue has implications not only for the inclusion of
synthesis models in the the VO framework but also for a proper usage of
synthesis models.
