Making Two Variables In To One

<xsl:variable name="seq1" select="'one','two'" />
<xsl:variable name="seq2" select="'three','four'" />

I need to output a new variable named "seq3" containing "one" "two"
"three" "four".

Unfortunately, I left Dr. Kay's heavy XSLT Reference book at home...
I imagine I'll find the answer in there but just in case...

- Ronnie Royston