<xsl:message>

A <xsl:message> is a mechanism for the stylesheet author to communicate with the person running the stylesheet.

<xsl:message 
  terminate = "yes" | "no">
  <!-- Content: template -->
</xsl:message> 
terminate

If "yes", the stylesheet processor is expected to stop processing after displaying the message

The content of the <xsl:message> element may be presented to the user in an application-dependent fashion. This could be a terminal message, a browser popup, nothing more than writing it to a log file or simply terminating the program without displaying the message at all (for example, in a server-side environment).