(on Substances that Deplete the Ozone Layer. ) An international agreement, signed in 1987, that serves to eliminate the use of compounds that have been linked to destruction of stratospheric ozone (including the chlorofluorocarbons and halons). Subsequent amendments and adjustments have been made to the Protocol (London, 1990; Copenhagen, 1992; Vienna, 1995) that have increased the number of compounds under regulation and accelerated the phaseout of the production of these compounds.