gistfile1.txt

<block type="page/html" name="root" output="toHtml" template="page/3columns.phtml">

        <block type="page/html_head" name="head" as="head">
        </block>

        <block type="page/html_header" name="header" as="header">
            // header block children
        </block>

        // some blocks
        
        <block type="core/text_list" name="content" as="content" translate="label">
            <label>Main Content Area</label>
        </block>
        
        // another blocks
    </block>