What are the different modes for Secure Sockets Layer Virtual Private Network or SSL VPN?

"There are three different modes for secure socket layer virtual private networks or SSL VPNs. The first is the clientless mode. This works at layer 7 of the network protocol and provides secure access to resources and content across the web. The clientless mode also supports common Internet file systems and can access databases and other online tools. The next mode is the thin client mode which also works at layer 7. This mode provides additional access to services such as Telnet, Secure Shell, Simple Mail Transfer Protocol, Internet Messaging Access Protocol, and Post Office Protocol, also known as POP3. The thin client is provisioned via a Java applet. The final mode is the thick client mode. This works at layer 3 and is also known as the tunnel mode. This mode provides all the services previously mentioned and is provisioned via dynamically downloaded VPM client software."