2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/13402Physical and numerical constraints in building up self-consistent population synthesis models are briefly analysed discussing their application to most of the current synthesis codes widely adopted in Galactic and extragalactic studies.8 pages + 4 PS figures, LateX, Proceedings of the Carloforte Meeting on "Evolving Evolution" (Carloforte, Italy, June 8-11, 1998). Edited by M. Bellazzini et al., in press. (see also http://www.merate.mi.astro.it/~eps/home.html)Astrophysicstext