Mordechai is a prominent legal (Halachic) work, which acquired wide authority, and was one of the sources of the "Shulchan Aruch" of Joseph Caro; it has also been printed as an appendix to the Talmud, since the Soncino edition of 1482. The work is written as a compilation of existing halakhic material, and also provides conclusions and results of long discussions in other works. It thus serves both a source of analysis, as well a source of decided law. Mordechai's knowledge of halakhic literature was extensive. He quotes the works, and written or verbal responsa, of about 350 authorities; in fact, "Mordechai" is now the only source for many Ashkenazi authors. He frequently quotes his teacher, Meir ben Baruch, and much of the "Mordechai" is written in support of the Tosafists, the last of whom were Mordechai's teachers.