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CM's lack of true LOS / WYSIWYG


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Jeff, the only people that know the real answers for certain aren't talking. It would be nice if BTS would respond, even if it was a "yeah it's a bug, and you'll have to live with it because we aren't going to fix it." At least we'd know one way or the other.

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Craiger

All your victory flag are belong to me

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Oh come on guys, they aren't answering....give them a break. it was posted today....they might not even be around.

Rune

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I am compelled to quote from the manual

My appologies, it's the rule's Lawyer side of me showing now......

from page 45 of the manual I received when I preordered when the game first shipped in July 2000.....

"Lines of Sight can be tricky around buildings, although most answers are easy once you think about it.In order to be able to look outside of a building without restrictions, a unit needs to be within a few meters of the outside wal (i.e. to peer throughwindows or other openings). If it futher away than 5 meters, it will still be able to see a few meters outside of the house, but not far beyond that.

When a building or a unit in a building is fired at, regardless if it is direct fire or indirect fire (from mortars for example), most of the fire will hit the outer walls of the building. Even then any units hiding within can still be hurt(by the blast, stones, glass sharpnel etc.). However, some rounds can also make it into the building and explode within, e.g. through hholes in the outer walls or roof, blasted doors or windows. Such shots can cause severe damage. There is even a very small chance that a round makes it into and THROUGH a building, exploding on the otherside-bad news for any troops lurking behind it!

The interiors of a house are abstracted and included into the combat resolution calculations. Although you can trace an LOS within the house without restrictions (though with limited range) the chance of emeny units hiding within the house and remaining unspottted is relatively high (imagine them hiding in another room), but drops dramatically the more time your units spend in the house."

Is there any other relevant section of the rule book I have over looked?

I sincerely believe the LOS through light buildings is intentional and I try to exploit it in every way I can. I am not so sure it is a bug at all. I'm just hoping we can get some straight foreward clarification as to exactly how LOS through buildings was intended to work by Steve and Charles. Perhaps it is intended to work exactly the way it is modeled now?

smile.gif

-tom w

[This message has been edited by aka_tom_w (edited 03-12-2001).]

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Originally posted by rune:

Oh come on guys, they aren't answering....give them a break. it was posted today....they might not even be around.

Rune

Actually I brought this up over a month ago. See the link I posted earlier for the thread.

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Craiger

All your victory flag are belong to me

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Originally posted by aka_tom_w:

I am compelled to quote from the manual...

That's all fine and good, but then they post this: There is a basic rule in CM -> "Nothing can shoot through houses". Put another way, in no way shape or form may any unit, regardless of what it is, shoot through house. Never. Not even in the strangest circumstances. LOS will not be calculated through a house.

So which is it? The two statements completely contradict each other. Also remember, we are talking LOS as well as LOF. It is one thing to talk about a round penetrating a wall, but it's another to talk about x-ray vision. I'm just trying to get a straight answer one way or another on this; with poor results unfortunately.

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Craiger

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I posted a similar screenshot some time ago...

No "official" response either.

It seems that everyone KNOWS that tanks can shoot and be shot through light buildings, but it is not "official".

[This message has been edited by ciks (edited 03-13-2001).]

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Ok, excuses and cop outs are not gonna work anymore. The problem is definitely one with movement, it happens with all houses, it is not a house edge/windows thing, vehicles can be very far behind the house and still be hit. Plain Evidence is now here for everyone to see in the form of two short movies:

Janne has sent them to me and they are really stunning.

One of them shows a scnene where a Stuart is killed behind a house by a Panther in much the same way I showed in my pictorial example, except it is a HEAVY house.

The other one is even better and shows a Greyhound being killed by a Panther when the Greyhound was 50m behind a church and he had entered that cover more than 1.5 seconds ago.

I made these sensational movies available for download at the link provided below, they are small in filesize and I encourage everyone to take a look (as soon as they are available).

Download here: cmlos movies - zipfile

(ciks I tried it and it works and sometimes does not work. I will definitely try to find a way to make it available - these movies are a must-see)

(note for newbies: The movies are saved game movies, load them as pbem files, no password needed.)

[This message has been edited by M Hofbauer (edited 03-13-2001).]

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It says "Page not avaliable"... frown.gif

EDIT: must be something with my Explorer, but i downloaded it with Anarchie (FTP client).

[This message has been edited by ciks (edited 03-13-2001).]

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Originally posted by M Hofbauer:

The problem is definitely one with movement, it happens with all houses, it is not a house edge/windows thing, vehicles can be very far behind the house and still be hit.

There may be a problem related to movement, but that isn't the only one involving LOS/LOF through buildings. I've been able to place vehicles during setup that can trace LOS through buildings. Obviously movement wasn't a factor in this case. There may be multiple bugs here.

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Craiger

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Originally posted by Wolfe:

I would have to assume this is intentional; BTS has known about it for some time:

LOS Completely Through a House: **Spoilers for 1 Long Day**

- Chris

Or maybe it's just a bug they don't want to have to tackle so it has become a feature? Is it ok to purposely use this bug/feature in a game against an opponent, or is that exploiting a loophole? Is it one more topic that should have to be discussed and agreed upon before the start of a game?

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Craiger

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I'm a bit late on this, but... It isn't a bug, is a known game limitation, there is a small differential between the calculations and what actually you see on screen... So when the game made the shoot calculation there was an hit, when you sow on screen the shoot went through the house...

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thruhouse2.jpg

That Pershing is shooting STRAIGHT thru a HEAVY building

I have some more shots of this to post but I will have to wait until tomorrow.

Tanks can and Do shoot straight thru buildings, I used to think it was ONLY light buildings but I did some more testing and they can shoot through heavy buildings and 2 story building too. I have some more screen shots to post tomorrow.

-tom w

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Well, since it is (among others) a movement out of LOS - thing, it also happens if TERRAIN gets in the way. Yes, you heard right. No more talk about light houses, windows etc. pp.- if the targeted vehicle enters the safety of being behind a hill the CM Magic bullet will tunel through the hill and kill the vehicle. And I've got the movie to prove it, courtesy of the same clever guy who has produced those other movies.

To quote from his email when he sent me that video:

"I modified the test scenario to have lower elevations behind the churches and could easily reproduce it. The Panther fires, the shell travels normally at first, then starts to plummet, goes underground, tunnels a few

hundred meters, goes under the church, reappears just a fraction of a second before impact and finally kills the Greyhound. "

He concludes (and I agree) from his testing that we have three different bugs / phenomena here:

-projectile flight path calculations

-LOS through buildings, esp. edges

-vehicles' LOS through a building when parked immediately next to them

I have the movie here. Email me if you want me to send it to ya, or tell me if I should add it to the geo****tties zipfile, or does anyone else volunteer to host it?

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Originally posted by aka_tom_w:

Tanks can and Do shoot straight thru buildings, I used to think it was ONLY light buildings but I did some more testing and they can shoot through heavy buildings and 2 story building too...

-tom w

I've not tested this with version 1.12, if it happens and NO ONE is moving, target or shooter, it is a different phenomenon from what I described 2 posts ago.

Just a question/idea, have you tested with small vehicles, like JeepMG , M8, M3 truck ? It would be nice to know if there is some connection...

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Hello folks, I made the movies M Hofbauer

is talking about.

Tanaka, I would say that what these movies show can not be explained by a small difference between engine calculations and their graphical representation.

A while back somebody argued that his shells were flying through enemy armor without causing damage and that he was using the realistic scale. BTS replied that the graphical representation and in-game calculations do not exactly match - the projectile can be shown flying through a tank when the engine had calculated a near miss.

What you see in the third movie is way off-balance. If you haven't seen a projectile tunnel several hundred meters underground and go under buildings, then kill the target, take a look.

The most logical explanation is that CM determines hitting and missing at the instant of firing, based on the conditions that applied at that very moment. If it was a kill, whatever the target might be able to do during the following seconds can't save it. It might drive behind a hill, behind buildings or woods, but the shell travels mercilessly through any obstacles and kills the target, because this was predetermined.

This is no LOS issue. The shooter needs to have LOS at the moment of firing, but after that it is irrelevant.

Apparently projectile collision detection is already implemented since they can unintentionally hit buildings when you are trying to shoot something else.

Possibly the only way to fix this would be to calculate trajectories dynamically when the shell is in flight. If I remember, this was suggested before and BTS replied that it would make a difference only in exceedingly rare cases. Like when Tank A is firing at a distant B and some third vehicle intersects the trajectory just at the most inappropriate time.

As far as I know, this 'you can't escape death' thing was not mentioned. Too bad cause it's much more common. The most annoying tank loss I've suffered this way was when Blastoise had his Sherman firing at my PzIV. The latter disappeared behind a hill, but alas, about a second later the shell arrived and tunneled through the darned crest, killing my panzer.

Subvet's concern with x-ray vision is

already explained by BTS. Somebody posted a picture showing LOS through the corners of three buildings and they replied this way:

"the underlying LOS grid doesn't match building walls perfectly (it would take too much memory and CPU time to do it more precisely). Sometimes it can be off by a bit, though the picture shown is the most extreme example I've seen. The LOS function

allows for a little "play" around corners and such."

Neither the shooter nor the target in the above example were anywhere near the buildings.

There might be yet another LOS issue that is visible in the picture aka_tom_w posted - if a unit is right behind a building, it can see through the middle.

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I'm not sure I understand why this thread exists. The passage in the rulebook is fairly clear: if your unit is close to the building (as it clearly is in the screenshot) there is a chance a round will pass straight through.

So whats the problem?

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ok, the TUNNEL FORCE movie can now be downloaded HERE (200k zipfile)

This movie is the one where zahl created a depression into which the Greyhound will disappear. The Panzergranate projectile with it's name on it will head right for the Greyhound, which means it will tunnel into the terrain, pass under the church, and exit on the reverse slope of the depression and then kill the Greyhound.

Again I can only encourage everbody to see for himself. The most recent movie by zahl also again shows that all the other (non-successful) projectiles fired at the disappearing but doomed Greyhound, will take an entirely different flight path roughly in the direction of where the Greyhound was situated when the shot was fired; i.e., they are not even being led to follow the moving target.

What this whole issue means to me is that the 3D world, esp. animations/movies, we are being shown are basically nothing more than eyecandy. The hit is predetermined by a non-dynamic, static formula just like in any other wargame (albeit a concededly way superior formula than any other to date), and after it has been decided by the dice whether there will be a hit or not then a nice colorful movie, a fireworks display, is produced by the game and shown to you to keep you fed and happy. We all sorta knew that before, still it's quite sobering when you fully realize it because it suddenly becomes so apparent.

yours sincerely,

M.Hofbauer

p.s.: nick, read the above posts again. There are three issues discussed here. Only one is explained in the manual (although even that has been declined in Steve's comment above), but the issue of projectiles flying through everything on their way to the target which has already escaped to safety is not covered by that. Please check the movie to see what I mean.

Again, anybody volunteering to host the movies? geocities is so unreliable...

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Guest Big Time Software

Subvet wrote:

It would be nice if BTS would respond, even if it was a "yeah it's a bug, and you'll have to live with it because we aren't going to fix it."

We have said this a few times before. There are inherent limitations in the game engine that we can't practically fix. it is NOT a bug, rather a design limitation. We have answered this many times before, but for some reason our repeated explanations don't seem to be understood by everybody. The problem with this thread is that people are mashing things all up, which is only confusing people more. All sorts of different visual outcomes are being attributed to DIFFERENT possible causes, when in fact it is the same thing causing all of them. It is really simple so I don't understand why some people are having such a hard time grasping this...

In the real world a round leaves its gun and travels until it impacts upon SOMETHING. That SOMETHING can be the target, a building next to it, or anything that happens to be directly in the flight path. With me so far?

Now, Combat Mission has two different limitations that kick in to the above. The first is that when a unit is shot at NO FLIGHT PATH IS CALCULATED. Instead, probability of a hit is calculated using a vast number of factors relevant at that particular millisecond.

If the a "hit" is scored then the round is graphically shown to fly and whack the target. If the target and/or the shooter are moving, there is a graphical chance that it might be behind something at the time it is hit.

If a "miss" is determined, the engine semi-randomly assigns the round an impact location (think of it as a "hit" defined above) and the shell graphically hits that location. Just like with a "hit", the impact location can be in a place that doesn't graphically make sense. However, a "miss" will check out intermediate blocking terrain because it can not be assumed that there is LOS/LOF to the miss impact location, unlike with a "hit".

The other problem is that the flight path of the round is not looking for random elements that might be in its way. This means vehicles or units in general. It even includes knocked out vehicles. It does, however, take into consideration static terrain like buildings and ground (slopes). Set up your own test ranges and you will see rounds impacting on these things all the time.

Basically, if the shot was determined to be a "hit", it is a "hit" regardless. Since LOS/LOF is requires when the shot is taken, there is no need to check intermediate terrain at all since by definition LOS/LOF rules out intermediate terrain blockage. At least at the second the shot is fired.

Zahl appears to understand this fairly well. Here is what he had to say above:

The most logical explanation is that CM determines hitting and missing at the instant of firing, based on the conditions that applied at that very moment. If it was a kill, whatever the target might be able to do during the following seconds can't save it. It might drive behind a hill, behind buildings or woods, but the shell travels mercilessly through any obstacles and kills the target, because this was predetermined.

This is no LOS issue. The shooter needs to have LOS at the moment of firing, but after that it is irrelevant.

Correct.

Apparently projectile collision detection is already implemented since they can unintentionally hit buildings when you are trying to shoot something else.

True for misses, since hits require LOS/LOF which by definition means no blockage. But it really is just a LOS/LOF check and where the blockage happens the round hits instead of the intended targeted area.

Possibly the only way to fix this would be to calculate trajectories dynamically when the shell is in flight.

Correct, but only part of the solution. There would also need to be a huge amount of TacAI work to simulate compensating for leading, wind, dropage, etc. Not only does the coding for this require a lot of time, but the CPU cycles necessary to carry it out as well. Too much to ask of us or the computer at this time.

If I remember, this was suggested before and BTS replied that it would make a difference only in exceedingly rare cases. Like when Tank A is firing at a distant B and some third vehicle intersects the trajectory just at the most inappropriate time.

This is correct. However, you can of course have situations where this is far more likely to happen than in others. For example, a dozen vehicles all mixed up on a level plane in close proximity to each other. But this is not something that comes up very often, so again the real chance of this being a factor in a game is low. It will happen, but the cure to fix the problem would kill the game.

Shooting through building corners is also related to this topic. We had to put some "play" into it because we do not track the exact location of the gun barrel. So once again, graphical portrayal is not 100% exact. And again, the limitation is on CPU calculations necessary for a host of game aspects (notably the TacAI once again).

Now to answer a couple of individual questions:

Jeff Dunquette wrote:

I think modeling Real WorldTM exterior ballistics and Real WorldTM LOS could go along way toward addressing some of these game quirks.

As I stated above, partially correct. However, reducing the abstraction of this one element has a cascading impact on the rest of the game. This means we would also have to be a refinement of all sorts of other game aspects in order for this to all work. Unfortunately, the coding and CPU load are too much. So to get CM that last 2% realistic we would have to drop everything and work on nothing but this issue for weeks, if not months, along with upping the minimum system requirements. Just not worth it.

Trajectory can be modeled with a function, so I don't get why this is such a big processor deal. Tank sims ala Steel Beasts already model Real WorldTM.

Trajectory is modeled in CM, but not on the fly for every shot. I have no idea what Al did with Steel Beasts, but the two games are different enough that it is a comparison of apples and oranges. For example, I think a game like Quake III looks to have exact trajectories done on the fly, but there are reasons why that is possible for Quake and still not for CM. Each environment is asking different things of the hardware, and therefore it is not possible to just say "this has it so why doesn't that".

Subvet wrote:

That's all fine and good, but then they post this: There is a basic rule in CM -> "Nothing can shoot through houses". Put another way, in no way shape or form may any unit, regardless of what it is, shoot through house. Never. Not even in the strangest circumstances. LOS will not be calculated through a house.

So which is it? The two statements completely contradict each other. Also remember, we are talking LOS as well as LOF. It is one thing to talk about a round penetrating a wall, but it's another to talk about x-ray vision. I'm just trying to get a straight answer one way or another on this; with poor results unfortunately.

You are seeing conflict between my statement and the manual only because you are not looking at the context of each seperately. I said nothing can shoot through houses in the context of the discussion about LOS/LOF in regards to moving vehicles, the limitations of when hits/misses are determined, and then how they are resolved. My statement was not meant to have anything to do with rounds going through buildings, which as Tom W pointed out is specifically mentioned in the manual. Also, "through" a house was, in the context of the initial discussion, defined as LOS/LOF being established through two or more walls of a building. So there is NO conflict between my statement and the manual.

Now... the only INTERESTING thing I see in this thread is the picture posted by Tom W. A vehicle should NOT be able to do that. Judging by the location of the vehicle the proximity to the house is the reason. In other words, flush up against the side of the house. So I tried to reproduce this in the Editor. I set up a test scenario and had very, very hard time reproducing it, but did in fact manage to put a vehicle in a spot where it could look straight through a house. It is obviously some sort of "sweet spot" as I couldn't get other vehicles to do it no matter how many times I repositioned them. I am having Charles take a look into it as this should not happen. Note that this probable bug appears to be limited to the exact placement of a vehicle flush up against a house, and therefore is not relevant to the rest of this thread.

I hope this clears up the questions that are (still) lingering about this LOS/LOF issue.

Steve

[This message has been edited by Big Time Software (edited 03-14-2001).]

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Steve BTS wrote: "Basically, if the shot was determined to be a "hit", it is a "hit" regardless. Since LOS/LOF is requires when the shot is taken, there is no need to check intermediate terrain at all since by definition LOS/LOF rules out intermediate terrain blockage. At least at the second the shot is fired."

well, I think it *is* an issue to worry about. Projectiles flying through solid terrain to hit a vehicle that couldn't possibly be hit anymore...

I just come from a quick DYO scenario I had made to test this out, several Tigers which can shoot at 2 halftracks running back and forth more than a kilometer away. Inbetween I have placed small hills which will allow small "windows", fields of view, through which the Tigers can and can not aquire the target.

Already in the first turn a halftrack was killed in the problematic manner which is at issue here - he was targeted and shot at while he was barely in view, but knocked out when he was clearly behind one of the inbetween hills which were blocking LOS at that point. When I rechecked the movie, sure enough the lethal round went THROUGH the hill which had moved into the flight path due to the neccessary leading of the moving vehicle.

In conclusio, I think this is a real problem which potentially affects all vehicles moving out of LOS which are being fired at just as they reach safety. It is easily reproducible and has practical relevance.

However I want to thank you (Steve) for explaining that it is a design limitation of the static formula used by CM. This means we now know what we are up to, and that we'll have to simply live with it. And even then, CM is (obviously) still the current king of the hill of it's genre, no doubt.

Yours sincerely,

M.Hofbauer

[This message has been edited by M Hofbauer (edited 03-14-2001).]

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Guest Big Time Software

M.Hofbauer wrote:

well, I think it *is* an issue to worry about. Projectiles flying through solid terrain to hit a vehicle that couldn't possibly be hit anymore...

Yes, it is an issue. But there are a LOT of issues in CM. There is only so much we can do. Therefore, no point in worrying about stuff we can't fix. This is still an extreme issue. You can certainly make test scenarios to show this behavior, but play the average scenario and count how many times this happens. That is how we determine if there is something that is in major need of attention. Once out of a couple hundred shots, compared with the massive uder taking to fix (even if the hardware can hack it) is spending our energy in the wrong place.

In conclusio, I think this is a real problem which potentially affects all vehicles moving out of LOS which are being fired at just as they reach safety. It is easily reproducible and has practical relevance.

Yes, but only in extreme cases. What you tested for, and what you were able to produce, was an extreme case. A brief view means less time to target and less time to fire. Therefore, the less time exposed still means a greatly reduced chance of being shot at, not to mention hit.

However I want to thank you (Steve) for explaining that it is a design limitation of the static formula used by CM. This means we now know what we are up to, and that we'll have to simply live with it.

Thanks for the thanks, but this explanation and admission of the engine's limitations have been made before, more than once in fact. So while I am happy that I could be of service, I just wanted to point out that this is not new information.

And even then, CM is (obviously) still the current king of the hill of it's genre, no doubt.

Thanks and we will steadily improve Combat Mission as time and hardware allow. These limitations can be overcome in time, and therefore they will be.

Steve

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los5.jpg

los10.jpg

los6.jpg

http://142.55.231.199/aka_tom/LOS/los6.jpg

http://142.55.231.199/aka_tom/LOS/los7.jpg

http://142.55.231.199/aka_tom/LOS/los8.jpg

http://142.55.231.199/aka_tom/LOS/los3.jpg

The directory they are all in:

http://142.55.231.199/aka_tom/LOS/

This is the Scenario:

http://142.55.231.199/aka_tom/LOS/kingofthehill.cmb

Here are some other pages:

http://142.55.231.199/aka_tom/LOS/los3.html

http://142.55.231.199/aka_tom/LOS/los6.html

http://142.55.231.199/aka_tom/LOS/los7.html

I am not ranting or raving. (honest)

But I do play this game to get my tanks into these positions knowing FULL well I can shoot straight thru buildings (ALL kinds of buildings) and get the first shot off.

I hunt my tanks slowly and deliberatly into buildings and routinely shoot thru them as though I can see and acquire LOS right thru both walls.

I am not claiming this is a bug. BUT I am saying these tanks in these pictures are NOT moving. They are getting LOS straight thru light and heavy buildings. So when the enemy AFV fires back I hope the building in front of me will "catch" some of the incoming rounds giving my AFV's a more defensive position.

This does not in fact work all that well in the game though because once the incoming round "rolls the dice" after the enemy has LOS its just a matter of luck whether they hit my tanks or not.

The scenario (unzipped, download as source I guess) is here:

http://142.55.231.199/aka_tom/LOS/kingofthehill.cmb

Thanks Steve for your insight and comments

I hope you find this helpful.

Until it is fixed I will continue to line my tanks up to aquire LOS directly through buildings hoping always to get that Lucky FIRST shot off without being detected.

I was the one who is constantly applying for that mythical job at BTS of gamey loophole tester if you recall. smile.gifbiggrin.gif

(Posted in Good humour of course)

For the record I like this "undocumented feature" just fine the way it is!

-tom w

[This message has been edited by aka_tom_w (edited 03-14-2001).]

[This message has been edited by aka_tom_w (edited 03-15-2001).]

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