I have found many different types of midrashic works. Some are, as far as I can tell, accepted as being authoritative. Meaning they were written (compiled?) by the sages in roughly the talmudic era. ...
Who wrote the anonymous explanations of Rashi printed within the text of Rashi? Sometimes when reading Rashi's commentary on the Torah one finds comments in parentheses that say things such as: ס"א, ...