(after mass analysis): The sum of the separate ion currents carried by the different ions contributing to the spectrum (this is sometimes called the reconstructed ion current).
(before mass analysis): The sum of all the separate ion currents for ions of the same sign before mass analysis.
Sources: Orange Book, 2nd ed., p. 206 (https://media.iupac.org/publications/analytical_compendium/) 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 1554 (https://doi.org/10.1351/pac199163101541)