No, ChemApp need not and cannot directly access any FactSage database. Thermochemical data from FactSage databases is made available to ChemApp (and ChemSheet, for that matter; i.e. any software that internally contains ChemApp) via ChemSage-style data-files, which are user-defined subsets of the databases available for FactSage. See section 7.7 for more information. For general information on data-files, see section 7.1, section 7.2, and section 7.3.