The generation and annealing of fixed positive and fixed negative charges are discussed in the context of neutral hole and neutral electron traps. The analyses are based on the results of experimental studies involving hydrogen ambient atmosphere annealing and/or electron injection of gate insulators in insulated gate field-effect transistors which have been damaged by 1.5-keV x rays. It is found, for example, that annihilation of fixed positive charge either by hydrogen annealing, or by electron injection results in indistinguishable "repair" of this defect, indicating that such repair probably involves loss of an electron by the hydrogen to an E'γ center. It is postulated that a new electron spin resonance (ESR) center representing fixed negative charge, Nn, which is derived from a large cross-section neutral electron trap might be detected under the proper conditions. Since large cross-section neutral traps (10-15 cm2) are known to exist in significant concentrations in insulators damaged with ionizing radiation, but have not been correlated to any structural defect detected using ESR, it would appear that they are not paramagnetic.