Task: Question Generation
Input (English): There were a number of avenues to upward social mobility and the achievement of nobility. Poland's nobility was not a rigidly exclusive, closed class. Many low-born individuals, including townsfolk, peasants and Jews, could and did rise to official ennoblement in Polish society. Each szlachcic had enormous influence over the country's politics, in some ways even greater than that enjoyed by the citizens of modern democratic countries. Between 1652 and 1791, any nobleman could nullify all the proceedings of a given sejm (Commonwealth parliament) or sejmik (Commonwealth local parliament) by exercising his individual right of liberum veto (Latin for "I do not allow"), except in the case of a confederated sejm or confederated sejmik.
Output (English): What is is called to nullify proceedings?