Process.Start() under asp.net?

According to msdn :

ASP.NET Web page and server control code executes in the context of the ASP.NET worker process on the Web server. If you use the Start method in an ASP.NET Web page or server control, the new process executes on the Web server with restricted permissions. The process does not start in the same context as the client browser, and does not have access to the user desktop.

Which account precisely is the "restricted permissions" ?

Example :

• I'm logged to win7 as RoyiN
• windows authentication is enabled
• Impersonation is enabled as BobK at web.config ( all over the site)
• The W3WP user is UserA (not network nor ApplicationPoolIdentity).

In C# I do Process.start("....cmd.exe...") ( with Startinfo credentials as : "Martin","Password","Domain")

• Who is the efficient account which finally runs cmd.exe ?

• To whom "restricted permissions" is actually regarding ?