The plane ideally marking the boundary between a phase and its environment.
Source: PAC, 1983, 55, 1251. (Interphases in systems of conducting phases (Provisional)) on page 1252 [Terms] [Paper]
Cite as: IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). Online version (2019-) created by S. J. Chalk. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook.