A handheld electronic device includes a reduced QWERTY keyboard and is enabled with disambiguation software. The device provides output in the form of a default output and a number of variants. The output is based largely upon the frequency, i.e., the likelihood that a user is likely to have intended a particular output, but various features of the device provide additional variants that are not based solely on frequency and rather are provided by various logic structures resident on the device. The device provides a learning function that allows the disambiguation function to adapt to provide a customized experience for the user. The learning function is disabled, however, when the relevant words are found to be in a special category for which frequency learning, i.e., frequency revision, is not employed.