habs/haer is the historic american building survey / historic american engineering record.
in the united states if a property is 50 years old, possesses historic
significance a red flag goes up if there is a state / federally planned,
designed or paid for project ( highway projects too ). there is a review
process called section 106 review, which is the historic preservation part of
the environmental assessment. if a property has enough significance
the government asks for a detailed written report, 4x5, 5x7 or 8x10 format
negatives and contact prints ( all archival &C ) and sometimes measured\drawings.
these are all submitted to the state historic preservation office ( shpo )
reviewed and sent to the habs office and then off to the federal archives.
over the years lots and lots of things have been documented from bridges
to greenhouses. and over the years the federal program has asked for only
"stuff" of significance on a national scale ( the best of the best sometimes ),
so ... if a property has local significance, the states record it to their own
standards. which are sometimes exactly like the federal government's, and
sometimes are not quite the same.