{
    {
        (bD)
            /(b_div)
                (zqN)(lbN)(hb!N)
                    /
                        /(hQ)(hR)
                            { /[hR]/[lbN][b!] | bR }
                            /(bRD)(bDR)
                                /(zqDR)(lbDR-unused)(hb!DR-unused)
                                    /
                                        /
                                            [bR]
                                        /
                                            /[hQ]/[0][b!]
                                        [pair]
                                    /
                                        /
                                            [bRD]
                                        /
                                            /[hQ]/[1][b!]
                                        [pair]
                                    [zqDR]
                                [bDR]
                            /[bD]/[bR][b_sub]
                        </[b_div][hb!N]>
                    /
                        /
                            [b0]
                        /
                            [b0]
                        [pair]
                    [zqN]
            [YC]
    |
        b_div
    }
    (bD)(bN)
        //[bD][b_div][bN]
|
    b_div
}