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January 3

How does su work?

How does su work? I assume it's simply a program file that is itself owned by root, and when run, asks the user for the root password. If the password is correct, it spawns a shell (which inherits the root privileges that su itself has), if it is incorrect, it exits. (For the sake of simplicity, I'm assuming the user only wants to su to root.) Is this really as simple as it works? If so, then if I have access to root privileges in the first place (and in the case of my own Linux system, I have them by default), there's nothing stopping me from writing my own su which always spawns a shell with root privileges, without the user having to do anything at all. The problem with that, of course, is security - if someone other than me came across this new version of su, it would compromise the entire system. Am I on the right track here? JIP | Talk 00:01, 3 January 2010 (UTC)[reply]

Yes, though I'm not sure why you mentioned "owned by root'. See setuid. Also http://www.coker.com.au/selinux/play.html is remotely related. --91.145.72.253 (talk) 00:15, 3 January 2010 (UTC)[reply]

see: 'man sudo', and no need to write your own version to not require a password: 'man sudoers'.—eric 00:27, 3 January 2010 (UTC)[reply]

Certain computers with hardware protection, e.g. a Trusted Platform Module, will refuse to execute programs such as su (and in fact, the entire boot sequence and kernel), unless the programs are cryptographically verified as a trusted version. On such secure systems (which are very expensive and are usually sold to banks and governments), it will be impossible to "replace" key system utilities like su with any modified version - let alone one designed to circumvent security. On other standard PC-like servers and computers, (depending on the operating system), it is trivial to replace "su" with some other feature. During my reckless youth, I recall messing with a guy's /usr/bin/ or /usr/sbin/ on Gentoo, I think we moved su to actually run ls or something. He deserved it, though. In this case, it was obvious that the correct program was not running (though it was the source of great confusion to the guy). If we had compiled some "phony" sudo or su program that intentionally appeared to be the correct utility, we probably could have obtained his password in plaintext, stored it, etc.; and done just about anything to the entire networked system. As always, physical access to the machine trumps every software security setting; only those very specialized super-secure computers with unique hardware and guarded system access are truly "secure". Nimur (talk) 14:23, 3 January 2010 (UTC)[reply]

Actually, I may rescind my claim that "physical access to the machine trumps every software security setting" and replace it with a more reserved claim, "...trumps most software security settings." If the hard disk drive were encrypted, it would be hard to do much damage "covertly" (though you could still wipe the data); but, as I recall, the poor sap had left a root logged in, so by the time I got there, any encrypted hard disk protection, if present, was already moot. Nimur (talk) 14:39, 3 January 2010 (UTC) [reply]

Windows Live Messenger 2009

Hi, my question is, If I have Windows Live Messenger 2009 and my accounty is somebody@hotmail.com can I add somebody@gmail.com to chat? Will this person receive the invitation? --190.50.71.52 (talk) 02:33, 3 January 2010 (UTC)[reply]

Better than asking here and hoping that someone will come along with the answer, would be trying it to see. However, I can tell you that on my MSN I do have some people who are logged in using Gmail, so, yes, it is possible. --KageTora - (影虎) (Talk?) 04:10, 3 January 2010 (UTC)[reply]

If they registered the Live account with their Gmail address then yes, you can. Hotmail account and Live account are separate (registering Hotmail will give you a Live account under that email address too, but Live account doesn't require a Hotmail address). --antilived^{T | C | G} 09:29, 3 January 2010 (UTC)[reply]

This is in answer to the question below, but Wikipedia is playing silly buggers, so I have to put it here. Thanks for the links, however they don't solve the problem. There is one thing that *may* fix the problem there, but I don't see why I should have to turn UAC off - then reboot (something I do very often with Vista) - delete the file - turn UAC on again - reboot again..... Forget Vista, it's a waste of space. Is there nothing I can do from Ubuntu? --KageTora - (影虎) (Talk?) 11:00, 3 January 2010 (UTC)[reply]

Permissions (Ubuntu + Vista)

I have a folder of pictures I made on GIMP, that I have transferred from my Vista machine to my Ubuntu machine. The problem I have now is that I can't move the folder from the Ubuntu desktop to anywhere else. I have copied it to my 'documents' folder, but now I can't get rid of the original, being told I don't have permission to do so. I have tried deleting the folder from my Vista computer, but get told the same thing. I am one who likes to have a totally clear desktop, and this folder doing nothing and having no reason to be there is doing my head in. Is there anything I can do about this? TIA! --KageTora - (影虎) (Talk?) 04:08, 3 January 2010 (UTC)[reply]

This link and this link may be of use to you. I hope this helps. JW..[ T..C ] 06:58, 3 January 2010 (UTC)[reply]

Learning Windows 7

Hi! I've had an XP laptop for a while now, but it's bust and needs upgrading. I've ordered one which runs Windows 7 - how easy is it going to be for me to pick up the new operating system? I was very proficient at XP... Also, I use programs such as Sibelius, PhotoshopElements, AVG9-Free, Inkscape etc.: are these compatible? Thanks! ╟─Treasury Tag►Speaker─╢ 10:46, 3 January 2010 (UTC)[reply]

If your old PC just needs upgrading, like you said, why buy a new PC with a new operating system which just looks different but doesn't do anything special? That'd be like having a Ford with a puncture and deciding to buy a new one *because it's pink* or something. In any case, if you were able to become proficient at XP, then I don't see anything stopping you becoming proficient at 7. Not a huge difference, really. There was a bit of a jump from XP to Vista (mainly in folders losing the 'My' in 'Documents' etc., and the Start button not actually having 'Start' written on it, plus being asked every few seconds if you are sure you want to do something, as if every action was part of an SAS mission deep in enemy territory. Being administrator and still having to 'run [individual program] as administrator' defies logic and being told you have no permission to modify a folder you put on the computer in the first place is infuriating beyond belief.). If you can handle that, you're sorted. Besides that, 7 is just eye-candy - no better, no worse than MS's previous attempts to make the world a better place. Oh, and there is no 'blue screen of death' in 7. MS have done away with that and given you a black one instead. For compatibility of individual programs, I'd suggest visiting their websites to see - you'd have to do that anyway just to download the software. While you are there, take a look to see if it says 'Windows 7 compatible', and if it does, then there is a good chance it is. Anyway, congratulations on your investment. --KageTora - (影虎) (Talk?) 11:11, 3 January 2010 (UTC)[reply]

Thanks for all that as far as it went... what I mean is, my laptop's screwed, I need to buy a new one, nobody much sells XP any more (certainly not to the specs I need), Vista's supposedly crap, so I chose to get one which runs Windows 7. Am I right in supposing that any program which is/was Vista-compatible would also be 7-compatbile? ╟─Treasury Tag►belonger─╢ 15:08, 3 January 2010 (UTC)[reply]

You can pretty much be assured of that, yes. And XP compatibility mode can usually handle the rest; at least, it does for me. I never had anything much against Vista, excpet it was too slow, and 7 is much better in that regard. The biggest difference, yes, is probably UAC. It's been toned down so it stays out of your way a bit more in 7 than it did in Vista, but if you haven't really used Vista, then it still might bother you for a while. KageTora's comment about being an administrator and still having to run things as an administrator being illogical is actually the whole point, and how it's supposed to work - the whole idea is to prevent people from just using admin accounts, thus granting permission to everything - read User Account Control.

Either way, if you're good with XP, it will take virtually no time to 'learn' 7 - don't worry about it. Ale_Jrb^2010! 15:19, 3 January 2010 (UTC)[reply]

Thanks for that! One or two other concerns: what is the difference between 64/32 bit, and which type is my laptop likely to have (brand new Fujitsu with Home Premium installed)? And am I right in thinking that Home Premium doesn't include XP Compatibility Mode? :) ╟─Treasury Tag►Lord Speaker─╢ 15:22, 3 January 2010 (UTC)[reply]

That is correct. You need at least Windows 7 Professional. But this does only cost marginally more than Home Premium, and all feature of Home Premium are included in Professional. --Andreas Rejbrand (talk) 15:29, 3 January 2010 (UTC)[reply]

(edit conflict) There are lots of differences between 32 and 64 bit arcitecture, but you'd be better off reading the article 64-bit for information about that. For most people, it's nothing more than 64 bit systems can support more RAM and higher-end hardware more effectively. This comes at the expense of running most home software, though, so it's almost guaranteed that you will have 32 bit unless you are specifically buying otherwise. Home Premium doesn't come with the XP virtual machine, but it can still run programs in compatibility mode, although you'll probably barely need it. Ale_Jrb^2010! 15:31, 3 January 2010 (UTC)[reply]

I would strongly disagree with the statement "This comes at the expense of running most home software". I run 64 bit Vista and there are few progams that will not run. --Phil Holmes (talk) 19:06, 3 January 2010 (UTC)[reply]

Read my reply below Comet's on how to run stuff Vista/7 doesn't. It's called dual booting XP and 7. ηoian ‡orever ηew ‡rontiers 19:09, 3 January 2010 (UTC)[reply]

As Ale_jrb said, you should read the 64-bit article. For Windows, some important changes are (a) 32-bit is limited to using only around 3GB of your RAM; (b) 64-bit Windows features both a "Program Files" folder (for 64-bit apps) and a "Program Filex (x86)" folder (for 32-bit apps), which itself causes some problems with configuring certain apps. Comet Tuttle (talk) 17:43, 3 January 2010 (UTC)[reply]

XP compatibility mode is a marketing scam. It's been there forever. It's called Microsoft Virtual PC. Runs on XP, Vista, and 7 (or rather it used to before Windows pulled support, but you can still download completely functional older versions). I even have it on my Vista computer. It's also free, and Microsoft offers a download (or it did) on it's website of a working disk image of XP (virtual PC's uses disk images), or you can use the recovery disk that came with your old computer. Don't expect "XP" mode to run anything more powerful than MS Word with an average computer cause virtual PC's are very inefficient. Personally, I'd get a XP-Linux (Debian)-7 computer, as windows 7 supports DirectX11 and XP supports a ton of software (ex. AppLocale, which Windows 7 does not support) as well as being a less resource intensive OS. You can always install XP on a computer with windows 7 and then install windows 7 on a separate partition with the recovery disk. But enough of what I'd do. In answer to your question on Windows Xp, it is still being sold by independent computer stores (local), and here with customization. Yes Microexpress computers don't have eye candy, but their computers have the least markup of major brands(ex. i7 laptop same specs costs $2000 vs $3000 alienware). Also, always get the 64-bit OS (there is a 64-bit professional version of XP.) ηoian ‡orever ηew ‡rontiers 18:58, 3 January 2010 (UTC)[reply]

The above angry rant should be disregarded. XP compatibility mode is useful. Comet Tuttle (talk) 20:27, 3 January 2010 (UTC)[reply]

I never said it wasn't useful. Just saying there are better options, especially when Virtual PC is free and that XP Compatibility mode is using Virtual PC. It also is not an angry rant. ηoian ‡orever ηew ‡rontiers 20:53, 3 January 2010 (UTC)[reply]

You are misleading readers. Virtual PC is free, but does not include a copy of Windows XP, which is not a problem with the XP compatibility mode of Windows 7. Comet Tuttle (talk) 20:57, 3 January 2010 (UTC)[reply]

The reader had XP. He/she has a install disk for it which can be used for Virtual PC. It was just one option I listed. I also stated that I personally would dual boot (or triple boot) as virtual PC's aren't an efficient way of running things. It was just a suggestion. If the user wanted to do resource intensive things, dual booting is better than using a virtual PC. In addition, Microsoft offers a free Disk Image of XP pre-activated on their site somewhere. Here's a link to a 2007 statement about it [1]. It's not insanely hard to remove the expiration date (ex. change system time). Disclaimer:I'm not using my virtual PC on Vista because the performance was terrible. ηoian ‡orever ηew ‡rontiers 21:01, 3 January 2010 (UTC)[reply]

Removing a reparse point

Backups in Win7 always fail for me with error code 0x81000037. The Microsoft website says the solution is to a remove a reparse point, but it doesn't say which point to remove and how to remove it! How do I fix this? --Glaesisvellir (talk) 17:31, 3 January 2010 (UTC)[reply]

Documentation, and particularly tool support, for NTFS reparse point is disappointingly patchy. This KB article describes how to create and destroy them (but not, I think, how to search a tree for one). This article links to some freeware that works with them (I don't know if they'll help). This API document describes how one can examine a file to see if it's a reparse point; one would hope that find.exe would have an option to use this API to find reparse points (in much the way Unix' find can search for symlinks) but I don't think it does. -- Finlay McWalter • Talk 17:50, 3 January 2010 (UTC)[reply]

For the record, 'dir /s /al', run from the root of the drive, should list all reparse points on the drive (/s makes it recursive, /al looks for reparse points in Vista and later OSes). You might need to run it more than once, adding additional /a options for 'h' and 's' (hidden and system files), but deleting system reparse points is very risky. Reparse points in Vista and later are effectively normal files; you use mklink to create them, but you can use normal deletion mechanisms to get rid of them. —ShadowRanger ^(talk|stalk) 17:50, 8 January 2010 (UTC)[reply]

How to open .pcx files?

I've got some .pcx image files in my computer, but I can't find any software that can open it. Is it possible to open it using windows? Because I know it is format for DOS. --142.161.75.164 (talk) 18:15, 3 January 2010 (UTC)[reply]

(I don't have a .PCX at hand to try this, but...) try converting it to something modern (like PNG) with Imagemagick's convert utility (e.g. convert foo.pcx foo.png). PCX is listed as one of the many file formats that Imagemagick understands. -- Finlay McWalter • Talk 18:22, 3 January 2010 (UTC)[reply]

IrfanView can open .pcx files, download available here —Preceding unsigned comment added by Kv7sW9bIr8 (talk • contribs) 19:03, 3 January 2010 (UTC)[reply]

On the Mac side, GraphicConverter can open just about anything. I also remember older versions of Photoshop had a PCX optional plug-in in the Goodies folder. --68.103.143.23 (talk) 05:08, 8 January 2010 (UTC)[reply]

Were can I find information about solving this problem

In early Oct. 2009 I purchased on eBay a brand new copy of Windows XP. The user had a 100% record for almost 700 transactions. I was on abusiness trip when it arrived and did not return until just before Christmas. I gave it and a new hard drive to my daughter who set about installing both on her computer. When it came time for activation she got a pop-up saying to enter a different product key which she did not have or to call an 888 number to activate the software online. Instead of activating Microsoft popped up another window saying the software was counterfeit and to send it to them instead of returning it to the seller along with the receipt. She therefore sent a message to eBay asking if she could return the CD for a refund but eBay woud not provide a means to file a dispute even though Microsoft would not activate it, eBay claims that it does not allow couterfeit operating systems to be sold through eBay unless the discovery is within 45 days of the sale (not the first activation date of the software). Is eBay a party to fraud here? Has Microsoft gone piracy crazy? Where can I find a list of options for dealing with this problem? 71.100.1.76 (talk) 19:18, 3 January 2010 (UTC) [reply]

Windows Genuine Advantage has been known to mess people up. I'm not sure if Microsoft ended activation for XP yet (as I remember reading somewhere that Microsoft was planning to end support). There's a number of ways to bypass activation (google), or you can try and get access to an Enterprise version (if you work at a white collar job, your company might have it), which doesn't require activation. Not really legal per se (as Microsoft licensed it to the company), but not many companies care if you do take a copy. As for consumer complaints, you would have to read Ebay's return policy (which I'm not familiar with), or if you purchased it through your credit card, you might have some protection there. ηoian ‡orever ηew ‡rontiers 19:38, 3 January 2010 (UTC)[reply]

Support will cease on April 8, 2014. They stopped selling XP and stopped creating new updates that aren't related to security in 2009. That's all.--Drknkn (talk) 03:34, 4 January 2010 (UTC)[reply]

Did you get in touch with the seller? They, not eBay, are usually who you want to contact first about bad products. It could easily be that Microsoft has done something wrong here, but if the seller claimed it was new and that the product key was new, then they are the ones who are in error here. Get in touch with them ASAP and ask about exchanging or refund. --Mr.98 (talk) 19:43, 3 January 2010 (UTC)[reply]

Did that already but no response. 71.100.1.76 (talk) 08:47, 4 January 2010 (UTC) [reply]

Now even the link to the seller (geoffrey_morris (636) 100% Positive feedback) is not working... 71.100.1.76 (talk) 13:55, 4 January 2010 (UTC) [reply]

To clarify, did you call the phone number Windows gave you for activatiion? The serial number has probably been used on another computer, so it's definitely not new. The only time I've seen screens like that was when in fact the serial number had been used on different machines (or the same machine with new hardware). In any case, calling that number has worked for me many times. Just tell the IVR system that the key has only been used on one computer and it should activate it.--Drknkn (talk) 03:22, 4 January 2010 (UTC)[reply]

Yeah, I went through the process and when it asked how many times it had been activated I said zero. When I called Microsoft and finally got through to an operator she hung up when I told her I had opened the package brand new and this was the first time it was out of the wrapper. If someone can activate by just looking through the clear plastic wrapper isn't this Microsoft's fault and Microsoft's responsibility and obligation to replace the software on the grounds of defective product or defective packaging resulting in a defective product? 71.100.1.76 (talk) 08:54, 4 January 2010 (UTC) [reply]

You can't see the code through the wrapper on a genuine MS product. It's on a card that's inside the opaque box, and sometimes inside an envelope too. Even the small-builder-OEM licences (which are distributed in a minimalist shrinkwrap with or without an install disk) keep the licence hidden until you open the shrinkwrap. If you could see the licence then it's not a genuine MS package; he's repackaged an old licence as new. 87.113.46.161 (talk) 19:08, 4 January 2010 (UTC)[reply]

This is an OEM package, not retail. You missed the eBay photo and description link above... 71.100.1.76 (talk) 21:32, 4 January 2010 (UTC) [reply]

Besides, Microsoft does not state anywhere that the way to differentiate pirated from genuine is if the product code can be seen through the wrapper leaving everyone to assume that the disk is required in addition to the code to be valid, prohibiting use of just the code for activation. 71.100.1.76 (talk) 22:13, 4 January 2010 (UTC) [reply]

No. Windows doesn't pay attention to the disk. It only cares about the serial number. When you activate Windows, it records the Windows serial number along with the serial number of your motherboard and the MAC address of your network card and then stores them in a remote database. If someone then tries to activate another copy of Windows XP using the same serial number but their computer has a different motherboard or network card, then you get the messages you saw. Try this:

Click on Start
Find and click on “Run”
Type regedit
Click the plus next to “HKEY_LOCAL_MACHINE”
Click the plus next to “SOFTWARE”
Click the plus next to “Microsoft”
Click the plus next to “Windows NT”
Click the plus next to “CurrentVersion”
Click “WPAEvents”
On the right panel, find “OOBETimer” then double-click it.
Now, delete all the values
Then type in this value without the quotation mark “FF D5 71 D6 8B 6A 8D 6F D5 33 93 FD”
Then click OK,
Then on the left panel right click WPAEvents, then click on Permissions
Then click System or SYSTEM, then Deny Full Control, then click OK.
Then exit the registry editor.
To verify that it works, go to Start, then “Activate Windows”, or go to Start, then All Programs, then “Activate Windows”. Or go to the Start menu, and click Run.
Then type oobe/msoobe /a
Then click OK.

It may sting psychologically, but perhaps the best way to resolve this is just to crack your copy of Windows using the above technique.--Drknkn (talk) 01:50, 5 January 2010 (UTC)[reply]

In my youth it would have been a no-no but since I did pay for the copy and the guy on eBay who sold it has a 100% rating with nearly 700 transactions and since Microsoft is not and has never been beyond reproach (for all I know they may have counted on extra sales by this method) and many of Microsoft's applications like Windows Media Player are a pain and none of the applications I use will run under Linux, etc. I personally have no qualm about handling it this way especially in absence of Microsoft's official assistance and cooperation and killing XP in four years so I'll have to ~~buy~~ rent Windows 7. Thanks. 71.100.1.76 (talk) 12:34, 5 January 2010 (UTC) [reply]

Buying a new motherboard and CPU and memory

I have nearly enough old computer parts including empty cases to put a complete desktop computer together. Can anyone give me a ball-park figure of how much it would cost to buy a modern motherboard, CPU and memory to get a reasonably future-proof system running Ubuntu? Thanks 78.147.11.181 (talk) 22:03, 3 January 2010 (UTC)[reply]

It depends on what specifications and requirements you want. If you want i7 cores, expect to spend anywhere from $600-1200 (retail, probably can find cheaper). Relatively low figure prices are $200 motherboard, $300 for the budget 2nd generation core (budget first generation is $200), and $200 of ram. The most expensive core (not worth it) is $1000, although the 2nd most expensive (2nd generation) is ~$650. If you want Core2 or AMD, it's much cheaper (and running Ubuntu should work fine with Core2). Don't forget the Gfx Card. If your looking for light use, you can get a complete 1GB Ram laptop for ~$550, so I'm assuming a light desktop would cost around $300.

ηoian ‡orever ηew ‡rontiers 22:18, 3 January 2010 (UTC)[reply]

Note that if you were building the above power-hungry computer, your "old computer parts" may not have an adequate power supply. As for my personal opinion, get an AMD Phenom II X4 set, for the best Bang-for-the-buck. (Hope I don't start an AMD-Intel war here.) Mxvxnyxvxn (talk) 03:40, 4 January 2010 (UTC)[reply]

You may also find it cheaper to look at the motherboard barebone bundles that some retailers offer, Novatech and others are quite good in this regarding price and some of them will also guarantee that the memory will be matched and working before shipment. Nanonic (talk) 23:34, 3 January 2010 (UTC)[reply]

Even corn, soybeans and flax are not future proof due to genetic engineering. Computer engineering is far, far worse because of bug correction and adding new hardware and software features/capability. The only protection is not to update. This works. Our church still uses an old computer with Windows 3.1 for writing letters and keeping records. The advantage is that there is no cause for worry about viruses or hacking but this comes in exchange for the loss of new features. 71.100.1.76 (talk) 09:12, 4 January 2010 (UTC) [reply]

Sorry, 71... but every part of the above post contradicts best-practices. First of all, I have no idea what you mean by "corn, soybeans, ..." how would these be future-proof, with or without genetic engineering? What does that even mean? As far as refusing to update, this is also a seriously flawed mindset. Most security vulnerabilities affect old, unpatched software. Windows 3.1 is now famous for introducing the Windows Metafile vulnerability - and since Windows 3.1 runs on a DOS stack with essentially no memory protection, but provides a "user-interface" with multi-tasking and invisible background-job capabilities, it is probably the single most vulnerable system to malicious software that can possibly run on any computer. And, since it has been around for more than twenty years, there has been plenty of time for malicious coders to play around with various exploits. Best-practice security is to update to the latest and most bug-free version. On extremely rare occassions, a "bug-fix" may introduce new problems, but the overwhelming majority of the time, bug fixes and upgrades actually fix bugs. Furthermore, if you are really using a Windows 3.1 system, you are no doubt running a serious risk of incompatability. If your hardware ever breaks and you seek to recover any of your data, you will have to go to much more effort to find a system which can still read 20-year-old formats, or can connect to antiquated hardware. Modern, high-performing computers can cost as low as $100 or 200; I bought a complete i920 system (i7 core) for under $1000; if the OP really wants to salvage old hardware, the most useful parts will probably be the hard-disk drives and the peripherals. Nimur (talk) 12:36, 4 January 2010 (UTC)[reply]

To play devil's advocate, I really disagree with you, Nimur, if 71's church PC is not connected to the Internet. If you have a working system, don't mess with it. Surely you've seen a firmware update that actually bricks a piece of hardware (happened to me last week). The large exception is, of course, that you need to patch security vulnerabilities if you're connected to the Internet. Comet Tuttle (talk) 22:00, 4 January 2010 (UTC)[reply]

Okay, it's a matter of user preference not to upgrade. But you can't call that "secure". 71 said there was "no cause for worry about viruses...." which is an invalid claim. Nimur (talk) 23:50, 4 January 2010 (UTC)[reply]

That might be true if the pastor or his secretary allowed our kids or anyone to run program on it which they do not. If a system is dedicated and not connected then there is not cause for concern, especially when a backup is made of the hard drive after each time the computer is used. 71.100.3.13 (talk) 13:21, 6 January 2010 (UTC) [reply]

BTW... reference to genetic engineering is to all of the potential changes to crops that can be made through GM and not to the herbicide gene in combination with the terminator gene. If herbicides like Round-Up will kill all but the GM plants with protection against it plus be GM'd not to reproduce then the future of crops is guaranteed for the companies allowed to do this and in the negative sense for all the rest of us. 71.100.3.13 (talk) 13:26, 6 January 2010 (UTC) [reply]

Looking for old software that combined decision trees with NPV

A few years ago I had a copy of some shareware software than ran on MS-DOS, in text mode only. It combined decision trees with net present values. Does anyone know what the name of this software was, as I would like to look at it again. I've spent a lot of time searching on the internet for this, but have not been found it. I have found one instance of similar Windows software, but this does not use NPV. Failing that, I might try writing something similar myself. The two hurdles would be the doing things with nodes such as joining and inserting, and getting a visual display of the tree - would these be achievable by an amateur programmer? Thanks 78.147.11.181 (talk) 22:16, 3 January 2010 (UTC)[reply]