How do I filter certain records in my XSL?

Example:

- <BOOK>
<CODE>10001</CODE>
<TITLE>TEST TITLE</TITLE>
</BOOK>

- <BOOK>
<CODE>10002</CODE>
<TITLE>TEST TITLE2</TITLE>
</BOOK>

In my XSL:

<xsl:template match="/">

Then how do I just filter where Book code=10001 ?

Thanks!