Census 2000 pl 94 171 techdoc
...geographic areas, such as counties, cities, census tracts, and blocks. State par-...Consolidated City (FIPS)...... CONCIT 5 69 A/N FIPS Consolidated City Class Code
https://www.census.gov/content/dam/Census/programs-surveys/rdo/TechnicalDocumentation/Census2000_pl94-171_techdoc.pdf