Dyes derived by condensation of phthalic anhydride with resorcinol (and derivatives) or m-aminophenol (and derivatives), of which fluorescein is the prototype (all such dyes have the xanthene nucleus)., ftaalanhüdriidi ja resortsinooli (või m-aminofenooli) kondenseerimisel tekkivad ksanteeni tuuma sisaldavad ühendid