Soon World Class players and some lucky others (hope to get in) will play a rematch of the "Naturalists vrs Scientists" classic.
This time Scientists will use "Moscito" a relay system based on 4 card majors that was created by Paul Marston (Australia). A german team leaded by Rene Stainer created a version and GIB (the leading computer bridge software) played a version called Moscito-Byte to win the computers bridge championship many times.
I'm not a super-expert but I'll try to introduce the ideas in Moscito and present some of its flavours.
MOSCITO (Majors-Oriented-Strong-Club = MOSC) is a system based in a strong club opening and 4 card majors. The system tries to open as many hands as it can to get into the auction frequently trying to find if possible a major suit fit at the safest level as soon as posible.
Light openings are the key to the system, the "oldets" version of Moscito used 10-14 openings and the modern variations tend to allow 8-14 openings where 8/9 HCP hands with good distribution are opened (Example 5431 hands). This means that almost all 10HCP hands are opened by rule.
The opening bids depend on the "flavour" of moscito being used, some variations are:
a) Modern variation
1c = 15+ any
1d = 9-14 with 4+ hearts
1h = 9-14 with 4+ spades
1s = 9-14 with 4+ diammonds
1N = 12-14 balanced without 4M

Same as before but 1s can be any unbalanced hand without 4M
c) German variation (this is almost natural and ACBL compliant)
1c = 15+ any
1d = 10-14 no 4M
1h = 10-14 4+ hearts
1s = 10-14 unbalanced with 4+spades
1N = 10-14 balanced with 4 or 5 spades
2c = 10-14 5+/4+ or 4+/5+ in the majors
Two level openings depend on the pair playing Moscito and the version being played.
Once the bidding starts Moscito uses "relays" to find out the distribution, controls and location of honors in pd's hands, the relay principle stablishes that one hand "asks" while the other "describes", if the hand being describe ends being the dummy the defense is blind with zero information about declarer's hand. If the inverse occurs: delcarer hand being known then you are playing an open hand.
Most versions convey that a relay shows an invitational or better hand and a second relay is game-forcing. Thus Moscito is in GF situations at very low levels of the bidding so forcing passes are very frequently and penalty doubles start very early (if GF then passes are forcing and dbls are for penalties usually). Moscito can describe accurately almost any hand from the common 4-4-3-2 patterns to the wild 8-2-2-1 patterns. You just have to learn the proper structures to use in relay sequences.
Denial cuebids and asking bids are used after the distribution is know to get the number of controls and specific location of honors to know if you have to play game, slam or a grand.
Luis