#pressure_unit  a unit measuring force per unit area
  supertype:  pm#unit_of_measure_for_a_physical_process (pm)  #unit_of_measurement  #pressure (pm)
  subtype:  #standard_atmosphere__atmosphere__atm__standardpressure  a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade
     subtype:  #STP__s.t.p.  standard temperature and pressure
  subtype:  #pascal__Pa  a unit of pressure equal to one newton per square meter
  subtype:  #torr__millimeter_of_mercury__mm_Hg  a unit of pressure equal to 0.001316 atmosphere; named after Torricelli
  subtype:  #pounds_per_square_inch__psi  a unit of pressure
  subtype:  #millibar  a unit of atmospheric pressure equal to one thousandth of a bar; "atmospheric pressure at sea level is 1013 millibars"
  subtype:  #bar.pressure_unit  a unit of pressure equal to a million dynes per square centimeter
  subtype:  #barye__barabsolute__microbar  the absolute unit of pressure equal to one dyne per square centimeter

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