[xsl] Insert running number with special start value

Hi,

I could not find a solution for my question in the FAQs, although I
think it could be trivial.

I have an XSL with a for-each loop and like to place a running number
into my output xml.

I could do this successful by using the following code:

   <xsl:for-each select="MyTag">
   ...
      <xsl:element name="running_number"><xsl:number/></xsl:element>
   ...
   </xsl:for-each>

It starts with value 1 and counts up till the loop ends.

But now I like to start with e.g. value 900 and not with value 1. What
is the easiest way to do this (the number attributes seem not to support
such thing)?

Best Regards,
Roland