The GES employs the VLT-UT2 FLAMES high-resolution multiobject spectrograph . FLAMES has two instruments, the higher-resolution UVES, fed by 8 fibres, and GIRAFFE, with about 130 fibres. In the present paper we concentrate on the much more numerous GIRAFFE spectra to thoroughly test our classification scheme; a similar analysis of the UVES spectra will follow later. We use only spectra obtained in the wavelength range with Hα line - HR15N setting (6470-6790Å, R=17000), for which the majority of targets selected by GES are open cluster stars. Along with ongoing GES observations, we also use all relevant ESO archive data, which are included to be analysed as part of GES. <P />(3 data files). <P />