We have analyzed oxide charging and interface trap generation induced by high-field tunnel injection in thin (200 to 250 Angstrom) thermal oxides of silicon prepared using rapid thermal oxidation (RTO). Constant-current Fowler-Nordheim tunnel (FNT) injection was used to stress aluminum gate MOS capacitors and to generate oxide and Si-SiO2 interface trapped charge. Analysis of both the flatband voltage and the gate voltage necessary to maintain constant current allows us to separate oxide charge generation from charge generated near and at the Si-SiO2 interface. The analysis reveals, in addition to background electron trapping at water-related trapping centers, the trapping of holes near the Si-SiO2 interface as well as the generation of interface charge and anomalous positive charge (APC) near the Si-SiO2 interface. The appearance of these charge components is consistent with a comprehensive model of oxide and interface charging proposed recently by DiMaria and co-workers, ad we make use of this model in discussing the extraction of information on oxide charging from FNT charging curves. In particular, we show that under simplifying assumptions consistent with device processing on a particular oxide, useful information concerning generation of specific charge species can be obtained.