Multiple criteria sorting aims at assigning alternatives evaluated on several criteria to predefined ordered categories. In this paper, we consider a well known multiple criteria sorting method, Electre Tri, which involves three types of preference parameters: (1) category limits defining the frontiers between consecutive categories,(2) weights and majority level specifying which coalitions form a majority, and (3)veto thresholds characterizing discordance effects. We propose an elicitation procedure to infer category limits from assignment example provided by multiple decision makers. The procedure computes a set of category limits common to all decision makers, with variable weights and vetoes for each decision maker. Hence, the method helps reaching a consensus among decision makers on the category limits, whereas finding a consensus on weights and vetoes is left aside. The inference procedure is based on mixed integer linear programming and performs well even for datasets corresponding to real-world decision problems. We provide an illustrative example of the method and analyze the performance of the proposed algorithms.