The main zone of 8-12 HCP is the foundation of a weak opening system because the frequency is the highest and it is much better to open these hands before the opponent has exchanged information then to overcall afterwards.
Besides this the fact of to open as frequently as possible to obstruct the opponent's bidding and to prevent them in their bidding exchange by reaching as quickly as possible, in case of no game prospects, a playable contract.
Reason why the majority of the openingbids are reserved for the main zone.

It is not usefull to reserve f.e. the opening bid 1 and/or 1 for the strong zone of 13+ HCP, because you loose an enormous number of biddingsteps. Reason why the opening bid of PASS has been introduced. Not as a form of a "trapping" pass, but to give you more bidding space than after any other opening. (see Fibonacci numbers)

Resulting that the weak zone of 0-7 HCP has to be bid through a fert. Common was to use the 1 bid.

The zones after PASS are:

The structure of opening bids in 1st/2nd position should be the same as the openingbids after PASS in 3rd/4th position. Including the strong zone, done by the two way 1 after Pass meaning 12+ any òr 6-11 balanced.

For the REGRESsion system it has been worked out strictly through all the sequences. Reason why f.e the 1 fert bid after Pass has a two way meaning too, to maintain for the balanced hands the same scheme (double transfers) as in the 1st/2nd balanced hand openings.

In the bidding examples the hands are often bid in reversed way too, to show you the symmetric design of the system.

Starting point is that the final contract should be played by the leader (R) of the auction and by the partner whose hand is stronger. The dummy wil not give any more information than already told. The opening lead wil be done to the unknown stronger hand and finally the majority of honours is shield. The leader will be the one who first receive information about his partners shape (that means balanced or singl./void ones)
In 13+ against 12+, because of all the previous relays, it depends on the sequence who will play the hand.
In a balanced opposite unbalanced (= with a void or singleton) hand, the partner with the balanced shape will be normally the captain because he will be able to evaluate the value of his longest suit, the honours and ruff tricks.

As uniform nomenclature (instead of 'captain', 'leader' 'servant' etc. etc.) I will use for the hand that is relaying and the hand that is responding to relays David Morgan's abbreviation suggestion: (clickhere for article)

R = Relayer, the hand that is relaying
RR = Responder to Relays, the hand that is responding to relays

Although originally, apart from the singleton scheme, not the aim of a weak opening system, for REGRESsion it is possible (if needed, because you give further information to the opponent) to ask for all shapes the exact distribution and keycards. Even a very strong hand can ask if partner has less than a Queen and for distribution.

For the balanced and main part of the unbalanced (unbalanced is with a singleton or void) patterns is the exact distribution and min/max in the certain pointrange known below the 4 level. For the extreme unbalanced the 2-suiters and min/max is known on the 3-level, exact distribution is known on the 4-level. The one suiters on the 4-level. (see efficiency index)

Sometimes there are very refined possibilities and methods to able you to get the wanted information.
It is up to you if you will use those ways.
In some schemes further (n.f). bids are treated at the same time and with completed sequences as well.
Reason why sometimes long versions- specially for alternative ones - exist. As you will see symmetry in the bids of course as usual. I do not want to deter you by such big schemes but all lies in the framework of options which are possible within the system. Up to you to alter or simplify. Anyway you wil have a handle.
See examples.

A Singleton or Void opening immediately gives partner information about a playable contract, because a singleton is usually accompanied by at least 3 cards in any other suit (for the singleton scheme shapes).
For the extreme singleton openings the longest suit is at least a 8 carder, or a 74 up to -94 or 65 up to 76 distribution. So a playable fit should be there too.
Those shortness openings are a corner-stone of the system. They have the priority regarding the first calls instead of mentioning your longest suit. Knowing the shortest suit gives more information than f.e. a 1 opening (5+ card) in a regular system of which the length of the other suits is fully unknown (from 0-5). A Singleton opening improves finding a playable fit, enables you immediately to evaluate the value of your longest suit, your honours and the ruff-possibilities.

And a big advantage is that by marking in a very early stage a singleton/void shape, you can stay low in case of a missfit and no game prospects. (see examples)

Because after the main opening bids in the 8-12 zone the average strength will be around the 20 points for both pairs. So you should be foccussed on creating the best conditions to win the part-score, therefore responses has to be non forcing (apart of a positive relay). At the same time you (could) make life difficult for opponent.

A relay is for above reason a positive action. Strictly bounded for the different opening bids.
Further relays are positive and normally forcing to game. Breaking a relay is non forcing, with a maximum you may bid game or in balanced situations bid further by taking over the relay. Breaking a relay after positive relays is forcing and has it meaning (asking for a stopper, start spiral scan, or start control bidding but trump does not count, etc.). For complete working out see the sequences for all the openings.

You can not use a positive relay as a kind of "cheap waiting bid" or pseudo-psyche, because in case f.e. you bid your partners suit with a minimum = non forcing, partner proceeds the bidding with a maximum else which you might don't want. And even more (although if BSis allowed -Psychic bids protected by system or required by system = Brown Sticker. (rule D) playing a WOS lives at pressure already and opponent has to count on your system agreements, your habits and full disclosure.
In case you can give a relay to avoid a misfit f.e. : possible within the system but to be mentioned on your cc

Although (apart of all the n.f. bids) the basic of the system is based on Relay-style. But not in a "Relaying to/for Relaying" way.
There is more than a simply (exact)-distribution knowledge. Reason why f.e. in the balanced openings 1H-2H there is a lot of playing-room to get more/pré-information than a simple distribution investigation. Such as min/max in the pointrange in combination with the shape, tophonours in a 5/6 card. Possibilities to use several "tools" within the relay-sequence and even then the possibility to pick-up again the complete relay-sequences if needed.
Hearing not an important control and knowing already that you will play game (and sometimes find your Moysian fit etc. in case of No stopper) you do not need to hear/know always the exact distribution. Bid your game. (no further info for the opponent). Hearing a control which is useless or giving you the information that there will be a lack regarding the possible other points left for the other suits, so that Slem will be out of the question, still gives opponent no further information. R's hand is unknown an preferably he will be the declarer. Many times -a bid in that suit = preferably not the "real"suit" - you have "manipulation tools" too, to get the declarer in the right hand to guard f.e. a King or a AQx. Not always of course, depends on the previous relay-sequence, "no system is perfect".
This pré-information can help the relayer too in his choice for using the correct tool (or combining it) for further investigation.

You will see that through the whole system a 4-point step in the ranges has been used. In the range itself a minimum and maximum , so in total 1 point margin. Shape it self does not count because R knows already if you are balanced or not and if balanced which sort. Specially in a slem try and asking for side values R can count what you could have within that 1 point margin. If you lie a Jack, it will not harm, but be carefull in other cases.
Quality of your hand is of course important. if you have f.e. AKQxx xx Ax Qxxx and you have to tell your partner, who has 12+, if you have 13-15 or 16-17. The choise is not difficult. In case R does a slemtry you will not disappoint him and your counting-partner after having asked for all the values, 'knows" why this is a maximum. Treat hands with maximum points but with too much 'soft' values (QJ) as a minimum.
f.e. in the 11/12 range = a maximum
QJxxx KQxx x QJx = minimum, QJxxx AJxx x QJx = minimum,
QJxxx KQJx x QJx = maximum, QJxxx KJxx x KJx = maximum

In balanced hands: Jack in combination with Ace or King does count, Queen doubleton if not QJ or QT up to you.
In Singleton/void hands: Jack/Queen Single does not count, K counts if not an Aceless hand, but f.e. 1st/2nd seat opening with a min/min and a King single and a worse main suit treat it as a 0-7. Devaluate 4333 shapes, specially if of poor quality.
As you will understand: vulnerable/quality of your opponent/your own skills :use pointranges as a guide but partner must depend upon you because all the instruments are based on that knowledge, see example.

And in the system itself in the 4432/4333 and a 8-12 or 6-11 opening in case of a maximum you have already 3 ways to describe your 4333, 2 ways for the 4432 regarding the quality. For a min/max 2 ways for the 4333.

As much as possible: SYSTEM ON.
Complete interference treatment will be given. See example.

First of all you are obliged towards your opponents that you control the system completely. Apart from the fact that you will loose any arbitration, it is not polite. Auctions take too much time and you will avoid that they ' hate' to play against you. Secondly, because all bids are highly artificial, you can correct a mistake hardly.
(see for fun one of the longest auctions possible within the system )

If no 100% control over the REGRESsion system, please do not play it in competition. Start with a simple WOS and more natural bidding style.

Besides you must be aware that most players are not used to WOS.
Reason why full disclosure is an important issue. Explain the bids completely even what else could be bid in certain circumstances and why not (till a reasonable level, depending on your opponent).

In this way you could gather supporters.

If you want to read/study this site off line go to downloads

•On top of each page always the total menu.

•For quick search (f.e. show me the 7222 in all pointranges or show me sequence: Pass - 1 - 1 - 2 ) go to the search page

• at the end of the pages (or in) always several back to's, depends where you came from

•I have used a colour code through all the sequences, text, schemes etc.

in Brown =R (Relayer)
in Blue = RR (Responder to Relayer)

lateron the R can become RR , then coded in black
and automatically RR becomes R ,and coded in green

and finally:
R can become again/return to RR , then in bright blue
and automatically RR becomes again/returns to R , and coded in grey

In this way you immediately can see in all the sequences or parts of a sequence who is the Relayer and the Responder and at the same time if there were changes in R/RR during the previous bidding sequence. Consequently f.e. a 1st/2nd seat opening in the 8-12 range is a RR colour coded one because partner is the R (Relayer = captain ;-).
So do not make the error of thought that brown is the starter of an auction.

I saw in a bridge newsgroup the following motto:

If they play / invent good methods then we will all benefit when we adopt the methods and if they play / invent poor methods then we will benefit by getting good scores off them.

which I would like to endorse.

REGRESsion is up to this moment for me more a study object, by lack of partners who are willing to learn the system for a few occasions only (HUM and BS regulations). So practise by playing on line and gathering experience if the modifications and all the alterations towards the original REGRES sytem are working indeed as foreseen will cause undoubtly that this system will be still in progress. I keep track of this progress to transfer it in all the pages and bid examples with the greatest accuracy. Sorry for eventual discrepancies.

I hope you enjoy it and for remarks and comments you always can contact me.

Marcel den Broeder

( 'he' in text to be read as: he/she)

Kxxx

6-11 s/v 4441up to 7330
OR s/v and L= Major or any 5/5

Kxxx

6-11 s/v 4441up to 7330
OR s/v and L= Major or any 5/5