U-1 Persons unemployed 15 weeks or longer as a
percent of the civilian labor force.
U-2 Job losers as a percent of the civilian labor
force.
U-3 Unemployed persons 25 years and over as a
percent of the civilian labor force 25 years
and over .
U-4 Unemployed full-time jobseekers as a percent
of the full-time labor force.
U-5 Total unemployed as a percent of the civilian
labor force (official measure) .
U-6 Total full-time jobseekers plus half part-time
jobseekers plus half total on part time for
economic reasons, as a percent of the civilian
labor force less half of the part-time labor
force .
U-7 Total full-time jobseekers plus half part-time
jobseekers plus half total on part time for
economic reasons plus discouraged workers,
as a percent of the civilian labor force plus
discouraged workers less half of the parttime
labor force.


MONTHLY LABOR REVIEW August 1982
http://www.bls.gov/opub/mlr/1995/10/art1full.pdf