character special

i want to output this character(for drawing table):
 which has the 18 as ascii code.
so i use :
<xsl:text>&#18;</xsl:text>
but i receive this error :
Character reference "&#12" is an invalid XML character.
in my xsl file i have:
<xsl:output method="text" version="1.0" encoding="ISO-8859-1"
indent="yes" omit-xml-declaration="yes" />



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