In competitive rowing, the following specialized terms are important in the corresponding aspects of the sport: Boat classes In competitive rowing events, abbreviations are used for different boat classes. Weight L, LWT or Lt: Lightweight rowing If not present the crew is open weight Age J: Junior(Under 19 years of age) B: Senior B (Under 23 years of age) Masters: over 27, includes a letter designation for the average age of the crew: A – 27 years of age and older B – 36 years of age and older C – 43 years of age and older D – 50 years of age and older E – 55 years of age and older F – 60 years of age and older G – 65 years of age and older H – 70 years of age and older I – 75 years of age and older J – 80 years of age and older If none of these abbreviations are present the crew is Senior A These age categories are effectively common to both FISA (Bye-Law to Rule 27) and USRowing (Rule 4–104) rules. USRowing also designates a AA category for ages 21–26, and defines Masters as over 21 rather than 27. There are no age restrictions for coxswains and their age is not factored into the average age of the crew. Gender M: Men's W: Women's Mixed: Equal numbers of either gender (excluding coxswain) Crew Size 1, 2, 4, 8: The number of rowers in the crew. It is common to use Roman numerals, especially when referring to a VIII. Discipline x: Sculling boat If not present then the boat is sweep-oar Coxswain +: Coxed (with coxswain) -: Coxless (without coxswain) If not present then the boat is coxless, except for an eight. Examples M8+ = Men's eight W4- = Women's coxless four (or "straight four") LM2- = Lightweight men's coxless pair BM1x = Men's single sculls under age 23 JW4x = Junior women's quad Masters WC2x = Masters women's double sculls with average crew age between 43–49 Mixed Masters 8+ = Eight with 4 women and 4 men as rowers and a coxswain of either gender Athletes Ambidextrous (UK) A rower who can row both on stroke side and bow side. (US) A rower who can row both on the starboard and port sides of the boat. In the US this is also known as bisweptual. Bow (or bow