Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Engineering.php
public static function getConversionGroupUnits($group = null)
    {
        $conversionGroups = [];
        foreach (self::$conversionUnits as $conversionUnit => $conversionGroup) {
            if (($group === null) || ($conversionGroup['Group'] == $group)) {
                $conversionGroups[$conversionGroup['Group']][] = $conversionUnit;
            }
        }

        return $conversionGroups;
    }
public static function getConversionGroupUnits($group = null)
    {
        $conversionGroups = [];
        foreach (self::$conversionUnits as $conversionUnit => $conversionGroup) {
            if (($group === null) || ($conversionGroup['Group'] == $group)) {
                $conversionGroups[$conversionGroup['Group']][] = $conversionUnit;
            }
        }

        return $conversionGroups;
    }
getConversionGroupUnits
Returns an array of units of measure, for a specified conversion group, or for all groups.

@param string $group The group whose units of measure you want to retrieve

@return array