According to Shabbatai ha-Kohen (the "Shach"), it was "known" that Rabbi Isserlein was not answering questions posed to him in the "Terumat HaDeshen", rather he actually wrote the questions and answers himself. Therefore (Shach concludes) unlike with other responsa, the parameters of the questions posed in the "Terumat HaDeshen" are themselves binding when alluded to in the answer. However, with the printing of the work "Leket Yosher" of Joseph (Joselein) ben Moses in 1903, it became apparent that the responsa were in fact based on actual questions, as the individuals who asked the questions are clearly identified there.