A data processing method and apparatus for maintaining and customizing a list of words, phrases, and abbreviations that are standard in a profession, industry, trade or occupation, for insertion of abbreviations from the list into the text, for converting selected words and phrases in the text to abbreviations, for converting selected abbreviations in the text to words and phrases, and for automatically converting a number of words and phrases to abbreviations, and abbreviations to words and phrases, throughout the text, comprising the steps of: storing in a memory a first data structure encoding a plurality of words and corresponding abbreviations; storing in a memory a second data structure encoding a plurality of abbreviations and corresponding words; selecting a word in the text to be converted to an abbreviation and converting the selected word to a corresponding abbreviation using the first data structure; and selecting an abbreviation in the text to be converted to a word and converting the abbreviation to a word using the second data structure.