The <cscm:when> tag is part of the multichannel framework that lets you build portals for mobile devices.
This tag renders its content for any client classification listed in this tag's "client" attribute that matches the client classification name. The client name comes from the HTTP request and is mapped to a client classification in <project>\WEB-INF\client-classifications.xml.
<tagName attribute="value">
</tagName>
client
Required (String) - The name(s) of the client classification(s) that will be shown the enclosed content. For more than one client name, use a comma-separated list.
<cscm:when client="pda,phone">
<img src="images/small_logo.gif">
</cscm:when>