QT - Not more than 2 swimmers per country.
ST - Not more than 1 swimmer per country, when there is no QT quota.
ST quota can be not more than 9 swimmers per event.
Altough if a swimmer has QT in one event and has ST in another event were no other swimmer from his country has qualified, this swimmer obtains ST quota.
This quota is not included in the 9 limit. This is mentioned in the event files as - qoe.
WC - when a country has no quota in men's or women's events can enter one swimmer per gender.