https://doi.org/10.1351/goldbook.M04014
A spectrum containing only ions made up of the principal @I03331@ of atoms making up the original molecule.
Source:
PAC, 1991, 63, 1541. (Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)) on page 1556 [Terms] [Paper]