The following is to cause a pause. For instance, between the variables in
<mi>i</mi><mi>j</mi>.
<xsl:template match="span[ @class = ’mi’ ]" >
<span class="space" title="speech-extra">
<xsl:text> </xsl:text>
</span>
<xsl:copy>
<xsl:apply-templates select="*|@*|text()|comment()" />
</xsl:copy>
</xsl:template>
-_-_-