It has to be noted that in some systems the presence of thresholds or conditions may limit the extent of the influence which preferences will ultimately have on the distribution of seats within a list. Although the voters can indicate their preferences, a number of conditions have to be fulfilled before they can be taken into account, such as thresholds or allocation of votes for lists with no preference to candidates at the top of the list. This generally results in a de facto closed-list situation, in addition to other obstacles to the effectiveness of preference voting (nomination districts, quotas for gender balance).