1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program.

"2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:"

1) Install CrossLoop on a Windows computer
2) Go to the default CrossLoop installation directory:
    C:\Program Files\CrossLoop
3) In that directory you will find the following files:
    - vncviewer.exe
    - winvnc.exe
    - VNCHooks.dll
4) Verify that we have not modified the binary program of TightVNC by comparing each of the files to files downloaded from the TightVNC website.

1) Go to http://www.tightvnc.com/download.html
2) Download tightvnc-1.2.9_x86.zip
3) Create a directory under CrossLoop
    C:\Program Files\CrossLoop\Original
4) Extract the ZIP file into
    C:\Program Files\CrossLoop\Original
5) Open a Command Prompt window and navigate to the directory you created
    c:\>cd "C:\Program Files\CrossLoop\Original"
6) Use the Windows FC program in a Command Prompt window to compare the binaries:

    C:\Program Files\CrossLoop\original>fc vncviewer.exe ..\vncviewer.exe
    Comparing files vncviewer.exe and ..\VNCVIEWER.EXE
    FC: no differences encountered

    C:\Program Files\CrossLoop\original>fc winvnc.exe ..\winvnc.exe
    Comparing files winvnc.exe and ..\WINVNC.EXE
    FC: no differences encountered

    C:\Program Files\CrossLoop\original>fc VNCHooks.dll ..\VNCHooks.dll
    Comparing files VNCHooks.dll and ..\VNCHOOKS.DLL
    FC: no differences encountered

I'd like to incorporate GPL-covered software in my proprietary system. Can I do this?

You cannot incorporate GPL-covered software in a proprietary system. The goal of the GPL is to grant everyone the freedom to copy, redistribute, understand, and modify a program. If you could incorporate GPL-covered software into a non-free system, it would have the effect of making the GPL-covered software non-free too.

A system incorporating a GPL-covered program is an extended version of that program. The GPL says that any extended version of the program must be released under the GPL if it is released at all. This is for two reasons: to make sure that users who get the software get the freedom they should have, and to encourage people to give back improvements that they make.

However, in many cases you can distribute the GPL-covered software alongside your proprietary system. To do this validly, you must make sure that the free and non-free programs communicate at arms length, that they are not combined in a way that would make them effectively a single program.

The difference between this and "incorporating" the GPL-covered software is partly a matter of substance and partly form. The substantive part is this: if the two programs are combined so that they become effectively two parts of one program, then you can't treat them as two separate programs. So the GPL has to cover the whole thing.

If the two programs remain well separated, like the compiler and the kernel, or like an editor and a shell, then you can treat them as two separate programs--but you have to do it properly. The issue is simply one of form: how you describe what you are doing. Why do we care about this? Because we want to make sure the users clearly understand the free status of the GPL-covered software in the collection.

If people were to distribute GPL-covered software calling it "part of" a system that users know is partly proprietary, users might be uncertain of their rights regarding the GPL-covered software. But if they know that what they have received is a free program plus another program, side by side, their rights will be clear.

• The first paragraph of our homepage on our website (www.CrossLoop.com) states:
  
  "CrossLoop extends the boundaries of VNC's traditional screen sharing by enabling non-technical users to get connected from anywhere on the Internet in seconds without changing any firewall or router settings."
  
  
• The "How it Works" page on our website (www.CrossLoop.com/howitworks.jsp) states:
  
  "The Windows version of CrossLoop uses the TightVNC software plug-in for screen sharing. We have included a binary distribution of the TightVNC program in the installation software of the Windows version of CrossLoop to save you the trouble of separately downloading and installing TightVNC. If you have any questions about your rights related to TightVNC (which is licensed under GPL), please see our detailed description of how we use VNC."
  
  
• The "FAQs" page on our website (www.CrossLoop.com/faq.jsp) states:
  
  " Is CrossLoop a GPL program?
  No, please see the full description of the CrossLoop shell program and the VNC program here.
  
  

  Where can I get the binaries and source code for the TightVNC program used by the Windows version of CrossLoop?

  The binaries and source code for the GPL-covered TightVNC program can be downloaded from our website here."
  
  
• The "Download" page on our website (www.CrossLoop.com/download.htm) states:
  
  "As part of these instructions (to install CrossLoop on your computer) you will be asked to accept the CrossLoop Terms of Service.  In some cases, the downloaded text of these Terms of Service shows an earlier Version than the definitive version which is currently Version 1.3, last revised 1/11/07 and found here. The Terms of Service includes two separate licenses. The first license is for the proprietary CrossLoop shell program and the second license is a GPL for the TightVNC program. If you have any questions about your rights to the software of these two programs, please see our detailed description of how we use VNC."
  
  
• Each page of the CrossLoop website contains a footer with a link to our VNC page which provides a detailed description of how we use VNC.
  
  
  
  

Can I release a non-free program that's designed to load a GPL-covered plug-in?

It depends on how the program invokes its plug-ins. If the program uses fork and exec to invoke plug-ins, then the plug-ins are separate programs, so the license of the plug-in makes no requirements about the main program.

If the program dynamically links plug-ins, and they make function calls to each other and share data structures, we believe they form a single program, which must be treated as an extension of both the main program and the plug-ins. In order to use the GPL-covered plug-ins, the main program must be released under the GPL or a GPL-compatible free software license, and that the terms of the GPL must be followed when the main program is distributed for use with these plug-ins.

If the program dynamically links plug-ins, but the communication between them is limited to invoking the `main' function of the plug-in with some options and waiting for it to return, that is a borderline case.

This section clearly applies to the CrossLoop shell because it uses fork and exec to invoke the TightVNC plug-in program. There are no function calls or shared data structures between the CrossLoop shell and the GPL-covered TightVNC.