key grouping with non-existing or empty elements

Hi,

        I have a question regarding grouping with key. 
Following is the input XML example:

<row row="1">
        <cell column="1">default_item1</cell>
        <cell column="6"></cell>
</row>
<row row="2">
        <cell column="1">default_item2</cell>
</row>
<row row="3">
        <cell column="1">lot01_item1</cell>
        <cell column="6">lot01</cell>
</row>
<row row="4">
        <cell column="1">lot02_item2</cell>
        <cell column="6">lot02</cell>
</row>

I have a number of items that need to be grouped by
lot (cell[column=6]).  As you can see, this cell is
optional.
I need to group rows that does not have cell[6] and
rows have cell[6] as empty string into the same group,
then process each of the row within the group via:
<xsl:apply-templates select="key('lineitemLotsKey',
$lotName)" mode="LineItem"/>

        The way I currently handling this is not very
elegent:
1. create a key on lot (cell 6) for all rows with cell
6 element:
        <xsl:variable name="LineItemLotColumn" select="6"/>
        <xsl:key name="lineitemLotsKey" match="//row[(_at_)row
&gt; $LineItemHeaderRow and
(cell[(_at_)column=$LineItemLotColumn])]"
use="cell[(_at_)column=$LineItemLotColumn]"/>
2. create a separate variable that contains rows that
does not have cell 6 element:
        <xsl:variable name="LineItemDefaultLot"
select="//row[(_at_)row &gt; $LineItemHeaderRow and
not(cell[(_at_)column=$LineItemLotColumn])]"/>
3. process $LineItemDefaultLot separately.
4. when process rows in key lineitemLotsKey, check for
string(cell[6]).  If empty, then does similar
processing as #3.

Of course, a slight improvement would be for #2,
instead of get all rows that does not have cell 6
element, also get all rows that has cell 6 element
equal to empty string.  That way, I would not need to
check for string(cell[6]) in step #4.

Is there a more elegent way than these above?

Thanks,

Xiaocun
xiaocunxu(_at_)yahoo(_dot_)com


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