static function getUnits()
    {
        return [
            static::PIECE,
            // Length
            static::METER,
            static::CENTIMETER,
            static::MILLIMETER,
            static::INCH,
            static::FOOT,
            // Weight
            static::KILOGRAM,
            static::GRAM,
            // Volume
            static::CUBIC_METER,
            static::LITER,
            static::MILLILITER,
            // Duration
            static::DAY,
            static::HOUR,
            static::MINUTE,
            static::SECOND,
        ];
    }
static function getUnits()
    {
        return [
            static::PIECE,
            // Length
            static::METER,
            static::CENTIMETER,
            static::MILLIMETER,
            static::INCH,
            static::FOOT,
            // Weight
            static::KILOGRAM,
            static::GRAM,
            // Volume
            static::CUBIC_METER,
            static::LITER,
            static::MILLILITER,
            // Duration
            static::DAY,
            static::HOUR,
            static::MINUTE,
            static::SECOND,
        ];
    }
static function getUnits ( ) { return [ static :: PIECE , // Length static :: METER , static :: CENTIMETER , static :: MILLIMETER , static :: INCH , static :: FOOT , // Weight static :: KILOGRAM , static :: GRAM , // Volume static :: CUBIC_METER , static :: LITER , static :: MILLILITER , // Duration static :: DAY , static :: HOUR , static :: MINUTE , static :: SECOND , ] ; }
Returns all the units.

@return string[]
Returns all the units .