amidium ions

Cations formally derived by the addition of one hydron to the N or O atom of an amide and N-hydrocarbyl derivatives thereof. In organic chemistry an unspecified amidium ion is commonly a carboxamidium ion
A00268-1
or
A00268-2
The term does not imply knowledge concerning the position of the cationic centre, e.g. PhC(=O)N+Me3N,N,N-trimethylbenzamidium.
Source:
PAC, 1995, 67, 1307 (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1315
See also:
PAC, 1993, 65, 1357 (Revised nomenclature for radicals, ions, radical ions and related species (IUPAC Recommendations 1993)) on page 1357