Introduction
       The Dictionary of Occupational Titles (DOT) was developed in response to the
       demand of an expanding public employment service for standardized occupational
       information to support job placement activities.  The U.S. Employment Service
       recognized this need in the mid-1930's, soon after the passage of the Wagner-Peyser
       Act established a Federal-State employment service system, and initiated an
       occupational research program, utilizing analysts located in numerous field offices
       throughout the country, to collect the information required. The use of this information
       has expanded from job matching applications to various uses for employment
       counseling, occupational and career guidance, and labor market information services.

       In order to properly match jobs and workers, the public employment service system
       requires that a uniform occupational language be used in all of its local job service
       offices. Highly trained occupational analysts must go out and collect reliable data
       which is provided to job interviewers so they may systematically compare and match
       the specifications of employer job openings with the qualifications of applicants who
       are seeking jobs through its facilities. The Occupational Analysis (OA) Program is
       currently supporting job analysis activity in the states of Michigan, Missouri,
       Massachusetts, and Utah, with North Carolina serving as the lead Field Center
       providing leadership and oversight.
       Based on the data collected by occupational analysts, the first edition of the DOT was
       published in 1939. The first edition contained approximately 17,500 concise definitions
       presented alphabetically, by title, with a coding arrangement for occupational
       classification.  Blocks of jobs were assigned 5- or 6-digit codes which placed them in
       one of 550 occupational groups and indicated whether the jobs were skilled, semi-
       skilled, or unskilled.
       The second edition DOT, issued in March 1949, combined material in the first edition
       with several supplements issued throughout the World War II period.  The second
       edition and its supplements reflected the impact of the war on jobs in the U.S.
       economy including new occupations in the plastics, paper and pulp, and radio
       manufacturing industries.
       The third edition DOT, issued in 1965, eliminated the previous designation of a portion
       of the occupations as ``skilled, semi-skilled, or unskilled'' and substituted a
       classification system based on the nature of the work performed and the demands of
       such work activities upon the workers.  These new indicators of work requirements
       included eight separate classification components:  training time, aptitudes, interests,
       temperaments, physical demands, working conditions, work performed, and industry.
       The fourth edition of the DOT published in 1977, contained over 2,100 new
       occupational definitions and several thousand other definitions were substantially
       modified or combined with related definitions. In order to document these changes,
       approximately 75,000 on-site job analysis studies were conducted from 1965 to the
       mid-1970's.  These studies, supplemented by information obtained through extensive
       contacts with professional and trade associations, reflected the restructuring of the
       economy at that time.
       Two supplements to the DOT have been released since the publication of the 1977
       fourth edition DOT, one in 1982 and one in 1986.  The 1982 supplement contained
       titles, codes, and definitions derived from Occupational Code Requests (see Appendix
       E) submitted by DOT users to local Job Service offices. The 1986 supplement
       continued this effort to publish new definitions as well as modify existing definitions
       consistent with new data collected.  The 1986 supplement contained 840 occupational
       definitions; of these, 761 were not defined in the fourth edition.
       Changes in occupational content and job characteristics due to technological
       advancement continue to occur at a rapid pace.  This rapid change to occupations
       coupled with user demand for the most current information possible has resulted in a
       revised approach to the publication of the DOT.  The OA network has focused its
       efforts on the study of selected industries in order to document the jobs that have
       undergone the most significant occupational changes since the publication, in 1977,
       of the fourth edition DOT.
       This effort of gathering data and writing/revising definitions in these selected industries,
       including ``new'' and revised definitions from the 1986 fourth edition supplement, has
       resulted in the publication of this revised fourth edition DOT.  This information is
       presented in the hope that it will provide the best ``snapshot'' of how jobs continue to
       be performed in the majority of industries across the country. Comments, suggestions,
       or criticism by DOT users concerning the content and format of this revised DOT are
       welcomed.