mt-Order with date headers/footers if mt:orderitem supported a “unique” attribute that it doesn't

gistfile1.html

<mt:Order>

    <mt:OrderHeader>
        <div class="site-activity">
    </mt:OrderHeader>

    <mt:Entries>

        <mt:DateHeader>
            <mt:OrderItem unique="true">
                <mt:setvarblock name="order_by">
                    <mt:EntryDate utc="1" format="%Y-%m-%d 00:00:00"> 0
                </mt:setvarblock>

                <!-- your date header code -->
            </mt:OrderItem>
        </mt:DateHeader>

        <mt:OrderItem>
            <mt:setvarblock name="order_by">
                <mt:EntryDate utc="1" format="%Y-%m-%d %H:%M:%S"> 1
            </mt:setvarblock>

            <!-- your blog entry code -->
        </mt:OrderItem>

        <mt:DateFooter>
            <mt:OrderItem unique="true">
                <mt:setvarblock name="order_by">
                    <mt:EntryDate utc="1" format="%Y-%m-%d 25:00:00"> 2
                </mt:setvarblock>

                <!-- your date footer code -->
            </mt:OrderItem>
        </mt:DateFooter>

    </mt:Entries>

    <!-- then the same for your action streams -->

    <mt:OrderFooter>
        </div>
    </mt:OrderFooter>

</mt:Order>