xsl::number from current note

Hi,

Do you know what's the difference between
<xsl:number level="single" from="*" count="SEC" format="1. "/>
and
<xsl:number level="single" from="." count="SEC" format="1. "/>

The second one sometimes does not work by giving error message:

XSLException Type is: XPathParserException
Message is: Expected node test.
pattern = '.'
Remaining tokens: ('.')

Thanks in advance.

Ming