According to style manual the rule natural=peak {name '${name|def:}${ele|height:m=>ft|def:}' } [0x6616 resolution 24] from default style should convert ele values from meters to feet, assuming ele is in meters, but this is what map shows for the following ele values: ele=500, map: ", 500 m" ele=500m, map: ", 500 m" ele=500ft, map: ", 152 m" So it seems to be doing right the opposite, converting from feet to meters. Also, with m=>ft rule, map should show ft units, not m. If I invert the rule from m=>ft to ft=>m this is what happens: ele=500, map: ", 46 m" ele=500m, map: ", 152 m" ele=500ft, map: ", 46 m" Now it seems when values are in feet conversion factor is applied twice. It seems when height: is used it always does a ft to m conversion first and then it applies what is specified in the rule. For the same examples, conv: filter gives the right values.