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>
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).