If a Character exists

Hi everyon, and thanks for the help again,, on what I thought would be
a simple, simple problem.

All I need to do is test if a character (specifically a period) exists
in a string

ie

<xsl:template match="AAA">
    <!--- If a period exits -->
    <p class="dindent"><xsl:value-of select="AAA"/></p>
    <!-- If a period does not exist -->
    <p class="indent"><xsl:value-of select="AAA"/></p>
</xsl:template>

Sorry, it does seem like a really simple question, but google wasn't
be good to me today.

Thanks for the help,

Spence