XSLT SELECT FOR-EACH element in list - list

Question

I'm currently using Biztalk for mapping. I have a source order document that contains all parts that are being ordered. The destination document needs to contain only rows that contain a valid item (CELL/#C004) in Valid/Sku list. The valid SKU list is cached on the webserver and gets refreshed as necessary. Rather than hardcoding the list of valid parts in the map, I'm using a c# script to call the webservice and the valid sku data is mapped into a xslt variable. Is this a good approach?
The best solution I'm thinking of right now is iterating over all of the Row data <xslt:for-each select"/SOURCE/ROWS/ROW"> and then doing a check to see if the item is in the list of valid items. Is there a more efficent way to do this? something equivelant to select ROW/CELL[#Name='C004'] IN valid/sku list?
Source Document
<SOURCE>
...other nodes
<ROWS>
<ROW type="D" index="0 ">
<CELL name="C001" visible="X">
<VALUE>80710693</VALUE>
</CELL>
<CELL name="C002" visible="X">
<VALUE>10</VALUE>
</CELL>
<CELL name="C003" visible="X">
<VALUE>100100</VALUE>
</CELL>
<CELL name="C004" visible="X">
<VALUE>04001-17</VALUE>
</CELL>
<CELL name="C005" visible="X">
<VALUE decimals="3">100.000</VALUE>
</CELL>
</ROW>
<ROW type="D" index="0 ">
<CELL name="C001" visible="X">
<VALUE>80710693</VALUE>
</CELL>
<CELL name="C002" visible="X">
<VALUE>10</VALUE>
</CELL>
<CELL name="C003" visible="X">
<VALUE>100100</VALUE>
</CELL>
<CELL name="C004" visible="X">
<VALUE>05001-17</VALUE>
</CELL>
<CELL name="C005" visible="X">
<VALUE decimals="3">100.000</VALUE>
</CELL>
</ROW>
</ROWS>
</SOURCE>
list of valid values (about 1,500 values) from a webservice call.
<Valid>
<Sku>04001-17</<Sku>
<Sku>04002-17</<Sku>
<Sku>04003-17</<Sku>
</Valid>

Answer 1

XPath would be /SOURCE/ROWS/ROW[CELL[#name = 'C004']/VALUE = $skus/Valid/Sku] or with XSLT 2 or 3 I would define a key <xsl:key name="sku" match="Valid/Sku" use="."/> and use the path /SOURCE/ROWS/ROW[key('sku', CELL[#name = 'C004']/VALUE, $sku)].