mixed labelled

https://doi.org/10.1351/goldbook.M03943
A @[email protected] compound is referred to as mixed labelled when the @[email protected] compound has more than one kind of modified atom e.g. CH3–CH2–[18O][2H].
Sources:
Blue Book, p. 515 [Terms] [Book]
PAC, 1981, 53, 1887. (Nomenclature of inorganic chemistry: II.1 - Isotopically modified compounds) on page 1893 [Terms] [Paper]