Observe the careless slander of Wikipedia from a poor speller [an ad hominem attack I could not resist making 
].
It will never have the authority of the Brittanica, but Wikipedia is sometimes more useful. Also, while anyone can post nonsense, corrections are rarely far behind, as in this example.
''Sceptical" with a “c” is British spelling, which I happen to prefer in this case. (I don’t use “colour,” though.)
Wikipedia is actually fairly useful for straightforward subjects like math or physics. On anything even remotely controversial – e.g. current events or personalities – it often devolves into a nuthouse. Are you really going to trust an encyclopedia entry that some paranoid loon could change on five minutes notice? Unfortunately, I suspect that would be the case here, as the chess community has an even larger pecentage of such persons than the general population. Though perhaps fewer than Wikipedia contributors.
A long winded interpretation, containing the decision of the Rules Committee: (this decision was a while ago)–
The rules state that the mechanism that indicates expiration of time (the “flag”) must be easily visible and recognizable to both players. Chapter 4 on equipment (chess clocks) also indicate that just about any mechanism (flag, alarm, beep, or light) or combination may serve as that indicator.
Note that it is the clock, itself, that is providing the signal, not a spectator or director. Therefore, no “outside influence” is involved.
It has been determined by the Rules Committee that a clock that freezes the time on both clocks at the expiration of a time control is just another mechanism to indicate that time has expired. Therefore, it complies with the rules.
There is no explicit rule that states that the clock MUST continue to run at the end of the sudden death control. The “both flags down” rules do not apply as both flags cannot be “down”, it is clear that time has expired, and it is clear as to whose time has expired first. Note that this does not prevent a player from ignoring or not noticing the flag fall. If the game continues, so be it. It is still up to the player who has remaining time to claim the flag fall. If the game should end by any other fashion prior to such a claim, the game is over and the time (or lack thereof) on the clock is irrelevant.
My advice is to make sure you understand the function of the clock being used before the start of the game. Therefore you are both playing on the same ‘field’ and the game is fair and legal. This is required in the rules (see chapter 4).
As far as the clock freezing at the primary time control (with a multiple time control game), this aspect requires some further discussion (does any clock actually do this?). As of now, I would rule that the clock meets the requirements in the rules (I could be wrong on this). Perhaps the rules need to be clarified to either allow or disallow such a feature.
If you have such a clock, and intend to use it, I would advise you to periodically check the move counter during a game to assure its accuracy. Remember that such a clock will depend on the move counter, which, in itself, is not to be relied on. Note that if no time forfeit claim is made before the conclusion of the primary TC move number, then the game continues to the next control regardless of the status of the clock. The frozen clock may need to be reset in such a case.
I see some scenarios (use example of 40 move primary time control):
Some clocks cannot be set with the delay on all time segments (only the final one) even though the rules state that delay must be set from move 1. Such clocks need to be set as if there is only one time segment by either adding the time of the sudden death to the time, or by resetting the clock for the second control. Some clocks do not have multiple time control capabilities. The same thing applies. For these two categories, I would add the second time control if seconds are displayed throughout, and inform my opponent that the primary control is over when the clock displays 59:59 (given that the SD control is 60 minutes). If seconds are not displayed throughout, I would set the clock for the primary control only, then at the appropriate move (e.g. 40) I would reset the clock.
This sounds like an attempt to alleviate the TD’s problem regarding the common argument that whoever’s flag fell first loses. This is not the rule.
The mere fall of the flag doesn’t end game. The flag is considered to have fallen when a player points this out. The “halt at end” feature infringes on the right of a player to claim a draw when both flags are down.
I agree with another poster that the rules should be clear and that the absence of a negative doesn’t imply a positive. As he said, the “hourglass isn’t forbidden” either, does that make it legal?
Terry Winchester
still true, even with “Halt at end”. The win is NOT automatic.
Rule 5G. states that a light or beep is allowed. Your arguement holds for those (or another non-subtle indicator) as well, as the light or beep draws attention to the clock, thus reducing the “right” to claim both flags down. The frozen display is just another level of notification.
I am merely pointing out the most recent decision on this subject by the Rules Committee.
You or I may agree or disagree with that decision.
NO. The only standard timers described in the book are specifically mentioned, the digital and the analoge clocks. An hourglass is neither. It is not a clock.
Enough said by me on this subject for now.
There is a difference between “permitted” and “required”, and between “not permitted” and “not required”.
That some clocks have automatic halt-at-end (you can’t turn it off) is a possible argument for halt-at-end being permitted. It is not an argument for its being required.
Likewise, that some clocks never halt at end is a possible argument for halt-at-end not being required. It is not an argument for its being forbidden.
That was my point – and I’m pretty sure it’s consistent.
Bill Smythe
IMO, the rule should be reviewed, and it sounds like you may agree! 
Until then, we have the rules as they are, and I’m reluctantly happy to abide by and enforce them.
Terry Winchester
There been a number of posters making a fair and accepted reason why the halt-at-end, or the other acts of the digital clock to show the end of time: are non-standard. Myself, would say the halt-at-end, or other acts of the digital clock like a beep would be non-standard. Like other members of this form, started out my career with the analog clocks. The reason why current analog players do not like the digital clocks, as the clock would freeze (halt-at-end), or have beeps for every move, or beeps at the end of the time control.
Since there was and still is a consorting between analog clocks and digital clocks, the standard to have the clocks not freeze, or have the beeps – has become the accepted organic standard of the players. It has not been the force of will with the directors to get players into this accepted mode. It has been an accepted standard with players that enjoy the analog clocks, just to make the digital clock as close to the same standard as an analog clock.
During the 1990’s, the players with digital clocks did have the clocks set with the beep on, and the halt-at-end more often than our contemporary society. It has become exceptional for an owner of a digital clock having the beep on, or having the clock freeze at the end of the last time control. If the owner of the clock wants the freeze on, would feel it is non-standard, again non-standard is still legal. Players do keep their clocks for a whole life-time, some players have clocks older than myself. There are some players with clocks from the 1950’s, 1960’s, 1970’s, one from the 1930’s. It would be imprudent to say a digital clock from the late 20th century would be unsuitable, just because the clock freeze.
If you don’t like the clock signalling the expiration of time, how can you stand to have the little red flag thingy swinging back and forth when your clock falls?
I do agree that beeps are rude, but halt-on-end is actually a less noticeable signal than the typical mechanical flag.
With the analog clocks, the flag can fall without understand it has fallen before both flags have fallen. The reason why others object to the halt-at-end, as it does not follow the same mode as an analog clock. It is not the question of the signaling of the expiration of one time, it is about the signaling of both time expirations for both players not just one.
With the analog clock, if you should win on time, you need to prove it with the amount of time you have on your clock. If you do not point out the win on time before your time has also expired, than the game will be a draw. As a player you should understand how much time you have left and your opponent. Do not watch the clock, only having an understanding of the time you do have and the time your opponent has.
Having the halt-at-end without the beep, is a poor way to deal with time management. The halt-at-end is not the best way to understand time management skills, as you let the clock settle time expiration not yourself. Having the clock show expiration for both players, is not a punishment for a draw. It only points out the need to build on time management skills during time trouble.