### 44.8 Volume, Area and Length

`GSL_CONST_MKSA_MICRON`

  The length of 1 micron.

`GSL_CONST_MKSA_HECTARE`

  The area of 1 hectare.

`GSL_CONST_MKSA_ACRE`

  The area of 1 acre.

`GSL_CONST_MKSA_LITER`

  The volume of 1 liter.

`GSL_CONST_MKSA_US_GALLON`

  The volume of 1 US gallon.

`GSL_CONST_MKSA_CANADIAN_GALLON`

  The volume of 1 Canadian gallon.

`GSL_CONST_MKSA_UK_GALLON`

  The volume of 1 UK gallon.

`GSL_CONST_MKSA_QUART`

  The volume of 1 quart.

`GSL_CONST_MKSA_PINT`

  The volume of 1 pint.