how to create an exclusion list from a variable?

HI all, i've this xml and i'm tryng to change the value of the attributes.
This is what i have:

<mets:div LABEL="Canto I">
                    <mets:div LABEL="Pagina 7">
                        <mets:fptr FILEID="file.00010"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 8">
                        <mets:fptr FILEID="file.00011"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 9">
                        <mets:fptr FILEID="file.00012"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 10">
                        <mets:fptr FILEID="file.00013"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 11">
                        <mets:fptr FILEID="file.00014"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 12">
                        <mets:fptr FILEID="file.00015"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 13">
                        <mets:fptr FILEID="file.00016"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 14">
                        <mets:fptr FILEID="file.00017"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 15">
                        <mets:fptr FILEID="file.00018"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 16">
                        <mets:fptr FILEID="file.00019"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 17">
                        <mets:fptr FILEID="file.00020"/>
                    </mets:div>
                </mets:div>

this is what i would like to obtain:

<mets:div LABEL="Canto I">
                    <mets:div LABEL="Pagina 7">
                        <mets:fptr FILEID="file.00010"/>
                    </mets:div>
                    <mets:div LABEL="Carta [1r]">
                        <mets:fptr FILEID="file.00011"/>
                    </mets:div>
                    <mets:div LABEL="Carta [1v]">
                        <mets:fptr FILEID="file.00012"/>
                    </mets:div>
                    <mets:div LABEL="Carta [2r]">
                        <mets:fptr FILEID="file.00013"/>
                    </mets:div>
                    <mets:div LABEL="Carta [2v]">
                        <mets:fptr FILEID="file.00014"/>
                    </mets:div>
                    <mets:div LABEL="Carta [3r]">
                        <mets:fptr FILEID="file.00015"/>
                    </mets:div>
                    <mets:div LABEL="Pagina 13">
                        <mets:fptr FILEID="file.00016"/>
                    </mets:div>
                    <mets:div LABEL="Carta [3v]">
                        <mets:fptr FILEID="file.00017"/>
                    </mets:div>
                    <mets:div LABEL="Carta [4r]">
                        <mets:fptr FILEID="file.00018"/>
                    </mets:div>
                    <mets:div LABEL="Carta [4v]">
                        <mets:fptr FILEID="file.00019"/>
                    </mets:div>
                    <mets:div LABEL="Carta [5r]">
                        <mets:fptr FILEID="file.00020"/>
                    </mets:div>
                </mets:div>

Hannon helped me to create this xsl that trasforms the values of all the
attributes (Michael Kay suggested me another way to do it, but it's difficult
to me to use it -he uses functions and namespaces- and it doesn't work), but,
now, i need to exclude some of these, in this case "Pagina 7" and "Pagina 13".
How can i build an exclusion list in the variable? thank you a lot to
everyone. i promise i will start to study Kay's manual early, and disturbing
no more.

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet exclude-result-prefixes="#all" version="2.0"
xmlns:mets="http://www.loc.gov/METS/"	xmlns:mix="http://www.loc.gov/mix/"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:rd="http://cosimo.stanford.edu/sdr/metsrights/"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:output indent="yes" method="xml"/>

<xsl:template match="@* | node()">
<xsl:copy>
<xsl:apply-templates select="@*, node()"/>
</xsl:copy>
</xsl:template>

        <xsl:template match="mets:div/@LABEL[matches(., '^Pagina [0-9]+$')]">
            <xsl:variable name="n">
                <xsl:number level="any" count="mets:div[@LABEL[matches(.,
                    '^Pagina [0-9]+$')]]"/>
            </xsl:variable>
            <xsl:attribute name="LABEL" select="concat('Carta [', if ($n mod 2
=
                0) then concat(($n + 1) idiv 2, 'v]') else concat(($n + 1)
idiv 2, 'r]'))"/>
        </xsl:template>

    </xsl:stylesheet>