query() of common.php

Hello all,
The below code is the most up to date implementation of query() in
common.php. The === seems to be a typo. Furthermore can anyone please
explain me the difference of query() and simplequery()? As far as I
understand with using simplequery()'s, I am only having a single result
set and when I use query(), I am having multiple result sets to operate
on. Is it the correct definition of the difference?

When will serious class documentation for PEAR start? I really want to
join in to help documenting classes as long as someone guides the staff.

regards,
-bd

    function &query($query) {
        $result = $this->simpleQuery($query);
        if (DB::isError($result) || $result === DB_OK) {
            return $result;
        } else {
            return new DB_result($this, $result);
        }
    }