Question: What is the Open age group in diving?
About the article "Diving", section "Canada".

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National Championships take place late in the year, usually during November.
The competition is held at the National Aquatic Centre in Dublin and consists of four events:  Irish Open Age Group Championships  Irish Open Senior Diving Championships  Novice Competition (8–16 yrs)  Novice Masters Competition (>25 yrs)  
In the United States, pre-college divers interested in three meter or tower diving should consider a club sanctioned by USA Diving or AAU Diving.
There is a group called Future Championship.
Top club divers are usually called "junior Olympic", or JO divers.
JO divers compete for spots on national teams.
Divers over the age of 19 years of age cannot compete in these events as a JO diver.USA Diving sanctions one East-West one and three meter event in the winter time with an Eastern champion and Western champion determined.
In the summer USA Diving sanctions a national event with tower competitions offered.
USA Diving is sanctioned by the United States Olympic Committee for selecting team representatives for international diving competitions including the Olympic Games.AAU Diving sanctions one national event per year in the summer.
AAU competes on the one, three, and tower to determine the All-American team. 
Technical diving (sometimes referred to as Tec diving) is a form of scuba diving that exceeds the conventional limits – especially depth and bottom time – of recreational diving.
Technical diving exposes the diver to significantly higher risks than recreational diving, including permanent illness and death, and therefore requires extensive experience, advanced training, and specialized equipment.
Technical diving also often involves breathing gases other than air or standard nitrox.
The term "technical diving" has been credited to Michael Menduno, who was editor of the (now defunct) diving magazine "aquaCorps Journal".
The concept and term, "technical diving", are both relatively recent advents, although divers have been engaging in what is now commonly referred to as technical diving for decades. 
Most provincial level competitions consist of events for 6 age groups (Groups A, B, C, D, E, and Open) for both genders on each of the three board levels.
These age groups roughly correspond to those standardized by FINA, with the addition of a youngest age group for divers 9 and younger, Group E, which does not compete nationally and does not have a tower event (although divers of this age may choose to compete in Group D).
The age group Open is so called because divers of any age, including those over 18, may compete in these events, so long as their dives meet a minimum standard of difficulty.
Although Canada is internationally a fairly strong country in diving, the vast majority of Canadian high schools and universities do not have diving teams, and many Canadian divers accept athletic scholarships from American colleges.
Adult divers who are not competitive at an elite level may compete in masters diving.
Typically, masters are either adults who never practiced the sport as children or teenagers, or former elite athletes who have retired but still seek a way to be involved in the sport.
Many diving clubs have masters teams in addition to their primary competitive ones, and while some masters dive only for fun and fitness, there are also masters competitions, which range from the local to world championship level.
There is some professional disagreement as to what all technical diving encompasses.
Until recently, nitrox diving was considered technical, but this is no longer the case.
Some say that technical diving is any type of scuba diving that is considered higher risk than conventional recreational diving.
However, some advocate that this should include penetration diving (as opposed to open-water diving), whereas others contend that penetrating overhead environments should be regarded as a separate type of diving.
Others seek to define technical diving solely by reference to the use of decompression.
Certain minority views contend that certain non-specific higher risk factors should cause diving to be classed as technical diving.
Even those who agree on the broad definitions of technical diving may disagree on the precise boundaries between technical and recreational diving.
One point upon which most scuba professionals generally agree is that any dive on which the parameters preclude the possibility of a "safe and direct ascent "to the surface should be considered technical diving of some sort, and must require specialized training and associated advanced certification.
Such situations would include:- Decompression diving (where the absorption of nitrogen gas in the diver's body tissues precludes a safe and direct ascent without decompression stops)- Cave, ice or wreck diving (where penetration inside the target venue (in a cave or wreck, or under sheet ice) precludes a direct ascent, because a horizontal path must first occur back to the point of penetration).
NAUI defines technical diving as "Any diving beyond the limits of the defined recreational diving limits which is currently set at the following - diving to 40 meters/130 feet, use of nitrox above 36%, multiple mix gas diving, penetration diving past the daylight zone and any form of decompression diving)."
PADI defines technical diving as "diving other than conventional commercial or recreational diving that takes divers beyond recreational diving limits.
It is further defined as an activity that includes one or more of the following: diving beyond 40 meters/130 feet, required stage decompression, diving in an overhead environment beyond 130 linear feet from the surface, accelerated stage decompression and/or the use of multiple gas mixtures in a single dive."
NOAA defines technical diving as "all diving methods that exceed the limits imposed on depth and/or immersion time for recreational scuba diving.
Technical diving often involves the use of special gas mixtures (other than compressed air) for breathing.
The type of gas mixture used is determined either by the maximum depth planned for the dive, or by the length of time that the diver intends to spend underwater.
While the recommended maximum depth for conventional scuba diving is 130 ft, technical divers may work in the range of 170 ft to 350 ft, sometimes even deeper.
Technical diving almost always requires one or more mandatory decompression 'stops' upon ascent, during which the diver may change breathing gas mixes at least once."
NOAA does not address issues relating to overhead environments in its definition.
The following table gives an overeview of the differences between technical and recreational diving: