The coordination samples show how events can be wired and how public parameters can be bound.
To understand the samples of any of a subpage you will need to have a look at the corresponding portlet.xml and the default-object.xml for this sample application.
On this page you can see one usage of shared parameters aliasing. Say you bought a portlet that displays the weather forecast for a location, and found on the web another portlet that displays the map for a zipcode.
Here we supposed that the two portlets are installed on the server without any change to their code or descriptors. The first portlet could define a public render parameter like:

   <public-render-parameter>
      <identifier>your_zipcode</identifier>
      <name>zipcode</name>
   </public-render-parameter>

The second portlet could have defined it like that:

   <public-render-parameter>
      <identifier>my_zipcode</identifier>
      <qname xmlns:coor="urn:jboss:portal:samples:coor">coor:zipcode</qname>
   </public-render-parameter>

We would like to alias those render parameters to a page parameter, so that without any change to the code we can pass a URL parameter by adding "?zip=20878" to define the zipcode to use for both portlets.
To do so we can either use the admin portlet or in our default-object.xml descriptor add the following:

   <coordination>
      <bindings>
         <alias-binding>
            <id>zip</id>
            <qname>zipcode</qname>
            <qname>{urn:jboss:portal:samples:coor}zipcode</qname>
         </alias-binding>
      </bindings>
   </coordination>

Now try to add "?zip=20878" to your URL to see it in action. Alternatively, you can also fill-in the form on the other portlet to define the page parameter.