In XPath 1.0:
You can use the built-in entities ' and "
In XSLT 1.0:
Alternatively, you can define your $Q and $APOS variables (put the content (the literal ” or the literal ‘ character) in the body of the xsl:variable, not in the select attribute).
In XPath 2.x (this also means XSLT 2.x and XQuery 1.x)
Simply escape an apostrophe by entering two adjacent apostrophes, escape a quote by entering two adjacent quotes, as defined by the XPath 2.0 language