Extracting highest values between 'found' positions

Hi

I have the following XML structure:

<panel>
	<rowdates>
		<date id="1">
			<start>051005</start>
			<end>051006</end>
		</date>
		<date id="2">
			<start>051007</start>
			<end>051115</end>
		</date>
		<date id="3">
			<start>051116</start>
			<end>051201</end>
		</date>
		<date id="4">
			<start>051202</start>
			<end>051231</end>
		</date>
		<date id="5">
			<start>060101</start>
			<end>060120</end>
		</date>
		<date id="6">
			<start>060121</start>
			<end>060131</end>
		</date>
	</rowdates>
	<property>
		<accommodation person="adult">
			<holidays>
				<nights>7</nights>
				<price>269</price>
				<price>289</price>
				<price>309</price>
				<price>359</price>
				<price>319</price>
				<price>329</price>
			</holidays>
			<holidays>
				<nights>14</nights>
				<price>304</price>
				<price>374</price>
				<price>-</price>
				<price>-</price>
				<price>-</price>
				<price>-</price>
			</holidays>
		</accommodation>
	</property>
	<property>
		<accommodation person="adult">
			<holidays>
				<nights>7</nights>
				<price>669</price>
				<price>789</price>
				<price>809</price>
				<price>959</price>
				<price>3299</price>
				<price>2929</price>
			</holidays>
			<holidays>
				<nights>14</nights>
				<price>3104</price>
				<price>7374</price>
				<price>999</price>
				<price>-</price>
				<price>99</price>
				<price>129</price>
			</holidays>
		</accommodation>
	</property>
</panel>

I need to match <date> elements within <rowdates> (which would be held
as parameters within the stylesheet), find their positions, then extract
the highest <price> element within those positions.

E.g..	Parameter1 '051005' matches the <start> child of <date id="1">
	Parameter2 '051201' matches the <end> child of <date id="3">
	So I need to compare <price> elements 1-3

	Parameter3 '060101' matches the <start> child of <date id="5">
	Parameter4 '060131' matches the <end> child of <date id="6">
	So I need to compare <price> elements 5-6

	.. and so on.

	Note that position 4 is unmatched and passes through 'as is'.

The result would look like:

<panel>
	<rowdates>
		<date id="1">
			<start>051005</start>
			<end>051201</end>
		</date>
		<date id="2">
			<start>051202</start>
			<end>051231</end>
		</date>
		<date id="3">
			<start>060101</start>
			<end>060131</end>
		</date>
	</rowdates>
	<property>
		<accommodation person="adult">
			<holidays>
				<nights>7</nights>
				<price>309</price>
				<price>359</price>
				<price>329</price>
			</holidays>
			<holidays>
				<nights>14</nights>
				<price>374</price>
				<price>-</price>
				<price>-</price>
			</holidays>
		</accommodation>
	</property>
	<property>
		<accommodation person="adult">
			<holidays>
				<nights>7</nights>
				<price>809</price>
				<price>959</price>
				<price>3299</price>
			</holidays>
			<holidays>
				<nights>14</nights>
				<price>7374</price>
				<price>-</price>
				<price>129</price>
			</holidays>
		</accommodation>
	</property>
</panel>

The added complication is that some of the input files may match some,
but not all the dates being searched. How do I cope with that?

Any suggestions greatly appreciated.

--
Kevin