Electronic typewriters and word-processing systems have been developed, increasing the difficulty in establishing the source of 'typewritten' material. Various new office machines, especially copiers, produce documents very different from those of the 1930s. With all of these problems, there has been an evolution and development of new methods for examining documents and new equipment to assist the examiner. Also throughout this period, certain office machines created challenging problems for several years, but subsequently have been replaced for the most part by contemporary equipment. They too are considered since the problem 1930s as well as those of the intervening years can still be encountered occasionally. (Author abstract)