#area_unit__square_measure  a system of units used to measure areas
  supertype:  pm#spatial_unit_of_measure (pm)  #unit_of_measurement  #surface_area (pm)
  subtype:  #square_inch__sq_in  a unit of area equal to one inch by one inch square
  subtype:  #square_foot__sq_ft  a unit of area equal to one foot by one foot square
  subtype:  #square_yard__sq_yd  a unit of area equal to one yard by one yard square
  subtype:  #square_meter__square_metre__centare  a centare is 1/100th of an are
  subtype:  #square_mile  an area of 640 acres
     subtype:  #section.square_mile  a land unit of 1 square mile measuring 1 mile on a side
  subtype:  #quarter_section__quartersection  a land unit equal to a quarter of a section (160 acres) and measuring 1/2 mile on a side
  subtype:  #acre  a unit of area (4840 square yards) used in English-speaking countries
  subtype:  #are  a unit of surface area equal to 100 square meters
  subtype:  #hectare  (abbreviated `ha') a unit of surface area equal to 100 ares (or 10,000 square meters)
  subtype:  #arpent  a former French unit of area; equal approximately to an acre
  subtype:  #b  (atomic or nuclear physics) a unit of nuclear cross section; the effective circular area that one particle presents to another as a target for an encounter
  subtype:  #dessiatine  a former Russian unit of area equal to 2.7 acres
  subtype:  #morgen  a South African unit of measure equal to about 2 acres
  subtype:  #perch.area_unit__rod  a square rod of land
  subtype:  #em__mutton__mut  the square of a body of any size of type
  subtype:  #agate_line__agateline__line  space for one line of print (one column wide and 1/14 inch deep) used to measure advertising
  subtype:  #column_inch__inch  a unit of measurement for advertising space

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