fetch value from processing instruction

Please help me to get rid of quotes!

In my XSLFO file I need a value from a processing instruction for retrieval
by a marker.
The processing instruction contains several values within quotes like:
<?p="1" a="2" b="3"?>
I created variables to fetch the values but can't get rid of the quotes.
What I need is just the numerical value without the quotes.

For example to fetch the value of p (I want the 1):
<xsl:variable name="info1" select="substring-after(.,'p=')"/>
<xsl:variable name="page.num" select="substring-before($info1,'"')"/>

However, in this second line I cannot use the " quote, so I tried:
<xsl:variable name="quote">"</<xsl:variable>
and then used:
<xsl:variable name="page.num" select="substring-before($info1,'$quote')"/>
but I still do not get the single number 1.

Any better solutions?

Thanks!


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