This document recommends a set of uniform procedures for the reporting of outgassing data. Its intention is to establish a consistent set of units, nomenclature, methods of data presentation, and certain experimental parameters in order that outgassing data from different sources is consistently reported so as to be useful to all. This document was prepared by a subcommittee of the Recommend Practices Committee of the American Vacuum Society and is an updating of a previous Recommended Practice published in 1965.