<!ENTITY connectivity                   SYSTEM "Connectivity.docbook">
<!ENTITY connectivity-ppp            SYSTEM "Connectivity/Ppp.docbook">
<!ENTITY connectivity-ppp-overview   SYSTEM "Connectivity/Ppp/overview.docbook">
<!ENTITY connectivity-ppp-modem      SYSTEM "Connectivity/Ppp/modem.docbook">
<!ENTITY connectivity-ppp-server     SYSTEM "Connectivity/Ppp/server.docbook">
<!ENTITY connectivity-ppp-client     SYSTEM "Connectivity/Ppp/client.docbook">
<!ENTITY connectivity-ppp-network    SYSTEM "Connectivity/Ppp/network.docbook">