& btgetrange()2
 
  Error Messages:
  * If insufficient arguments are provided the function will return #
    -1 FUNCTION (BTGETRANGE) EXPECTS BETWEEN 3 AND 7 ARGUMENTS
  * If <MapObj> is not a object with the XCODE flag the function 
    will return #-1 INVALID MAPDB
  * If <MapObj> is an object with the XCODE flag but not a map 
    object the function will return #-1 OBJECT NOT HCODE
  * If an argument of xy[z] sets is outside the boundaries of the 
    map the function will return #-1 INVALID COORDS
  * If an argument of a UnitDB is invalid the function will return #
    -1 INVALID MECHDBREF
  * If an argyment of a UnitDB is not on the map specified in 
    <MapObj> the function will return #-1 MECH NOT ON MAP
  * If one xy[z] set specifies the z argument, but the other does 
    not the function will return #-1 INVALID ARGUMENTS
  * Any other error will return #-1 GENERAL ERROR 
 
  Example:
  Given that #1234 and #2345 are valid units. Given that both units 
  are on MapObj #62, located at 0,0 and 10,10.
   > think btgetrange(#217,#1234,#2345)
  13.228762
   > think btgetrange(#217,#1234,7,12)
  13.000007
   > think btgetrange(#62,14,1,10,10)
  9.643657