The photometric system of J-PLUS will be tied to the same system as HST, SDSS and Gaia. This is defined by a set of fundamental or pillar spectrophotometric standard stars that are ultimately tied to the spectrum of Vega.
The fundamental SSSs are those presented in Table 1 (to be published soon). However, since this are just a few, an extended sample of SSSs will be used. For this we will used those SPSS from Gaia (Pancino et al., 2012). Until the publication of the spectra of the SPSS from Gaia, we will rely on other common sources of spectrophotometric standard star like the CALSPEC library.