Manager vs host-manager

[gb1071nx]

I've found in the $CATALINA_HOME/server/webapps directory these two
apps: 
 
manager (know what this is)
host-manager  (don't know what this is)
 
I've searched the contents of 
http://tomcat.apache.org/tomcat-5.5-doc/manager-howto.html
 
but can't find a reference to the TC 5.5 deployed app "host-manager". 
 
 
Can someone shed some light?