GetResponse can be used by commands to get a response.

ConnChannel listens for connection requests.

In receives incoming messages.

Out houses outgoing messages.

PassBack returns a response to a command if requested.

PassBackID houses ID waiting for a response.

ScriptIn listens for script run requests.

ScriptRet houses return codes from scripts.

Vars is an instance of ShellVars.

Opt houses some options.

ShellVars house some important structs, so they can be accessed elsewhere.