Choice behavior and preferences typically involve numerous and subjec- tive aspects that are difficult to be identified and quantified. For this reason, their ex- ploration is frequently conducted through the collection of ordinal evidence in the form of ranking data. Multistage ranking models, including the popular Plackett- Luce distribution (PL), rely on the assumption that the ranking process is performed sequentially, by assigning the positions from the top to the bottom one (forward order). A recent contribution to the ranking literature relaxed this assumption with the addition of the discrete reference order parameter, yielding the novel Extended Plackett-Luce model (EPL). In this work, we introduce the EPL with order con- straints on the reference order parameter and a novel diagnostic tool to assess the adequacy of the EPL parametric specification. The usefulness of the proposal is illustrated with an application to a real dataset.