public Number getPercentComplete(int row, int column, int subinterval);

    /**
     * Returns the percentage complete value of a sub-interval for a given item.
     *
     * @param rowKey  the row key.
     * @param columnKey  the column key.
     * @param subinterval  the sub-interval.
     *
     * @return The percent complete value (possibly <code>null</code>).
     *
     * @see #getPercentComplete(int, int, int)
     */
    public Number getPercentComplete(Comparable rowKey, Comparable columnKey,
                                     int subinterval);