LECTURA. Scotus's first set of lectures on the Sentences. The date of this work is unclear, the genre is probably that of notes. That is, they may not directly reflect the classroom lectures. Lectura I-II are a discrete work, Lectura III may not actually be part of the same sequence at all and could be a Reportatio.
ORDINATIO. An Ordinatio is the official version of a work prepared by a master for publication (from "ordinare). Scotus' Ordinatio incorporates the Lectura text, and was begun in 1302. It covers books I-IV. The order Scotus lectured was probably I-IV-II-III; and books I and IV contain a great deal of revisions that Scotus indicated be included in the final copy (these are the "extra's"). Scotus never finished this work, so in the strict sense it is not an Ordinatio at all. He was probably working on it at Paris as well as Oxford, which means that the interpolated passages from the Reportatio might be there at Scotus' direction (the Vatican edition normally excises these). This work has been commonly seen as the "summa" of Scotus, that is, where one can get Scotus' standard or normative opinion of things. This may not be the case.
REPORTATIONES. A Reportatio is a student report of a lecture, based on the oral presenation in the classroom. There are several sets of Reporationes associated with Scotus. For example, there is one allegedly from Cambridge, and a set from Paris. These cover all four books, and were probably delivered 1302-1305 (1305 was the year of Scotus' regency, in 1303-4 he was exiled) The "A"set is generally seen as the best of the reports, and it is indeed fairly polished. If one were to read a work of Scotus all the way through, I would recommend this one. Book I was apparently examined and approved for publication by Scotus himself; this is not true of the other books. Their exact doctrinal weight is thus somewhat ambiguous.
COLLATIONES. A set of conferences Scotus held with his students. There is both an Oxford and Parisian set. They are probably from later in his career. The format is a series of pro and con arguments, without any magisterial determination. So one would probably not cite one as evidence of Scotus' opinion's on a subject. Collatio 23, for example, is about analogy. It is the only passage in Scotus' writings where he analyzes arguments from Aquinas (taken from the Summa contra gentiles). But while he does criticize the arguments themsevles, he does not give a final answer to the problem. A few have been critically edited, no critical edition of the whole is even on the table at this point (well, it's listed as part of the Brepols series; but no one is actually going to start work on it for at least thirty years).
QUAESTIONES SUPER LIBRUM ISAGOGE PORPHYRII.
QUAESTIONES SUPER PRAEDICAMENTA ARISTOTELIS.
QUAESTIONES IN LIBROS METAPHYSICORUM ARISTOTELIS. A question-commentary rather than a literal one, as readers will be familiar with from Aquinas. Only books I-IX are genuine. This work is traditionally seen as early, but parts of book VII postdate the Lectura, and book IX at least has the appearance of a finished treatise. There are also some "extra's" and "additiones" that show that Scotus did spend some time revising the work. It has been edited as vols. 3-4 of the Opera Philosophica series from St. Bonaventure University.
QUAESTIONES DE ANIMA. This covers books II-III of the De anima. It has the appearance of a compendium for students of common franciscan positions with replies to standard objections to the franciscan positions. It is commonly seen as early, and Parisian, but I think the editors are begging the question on this. My co-blogger Michael showed in his dissertation that the editors screwed up a bit on the spiritual matter question, which is dependent on Gonsalvus of Spain's Quodlibet (disputed ca. 1302-4). When I read the work, the final questions on univocity and the object of the intellect seemed to me to be simply abbreviations of the Ordinatio rather than the first breakthrough of a new position (though this might be hard to prove). Further research on this matter is required.
QUAESTIO DE FORMALITATIBUS/LOGICA SCOTI. This is a fragmentary question disputed by Scotus at Paris (all of which info was proven by Dumont; Balic had thought the text to be one of the Collationes) on the subject of certain inferences that could be allowed when the formal distinction is at play. One issue is whether formal distinction can be derived from formal non-identity, which Scotus allows here; he had denied it in the Ordinatio.
TRACTATUS DE PRIMO PRINCIPIO. A treatise proving the existence and essential properties of God; there has been some debate of its relation to the commentaries on the Sentences. It appears that the majority of it is derived from the Ordinatio. Scotus gave the work over to a socius, who did not understand Scotus' directions clearly for there are some errors and irrelevant material thrown in. This treatise was cited early on by Scotists like Petrus Thomae and Antonius Andreae.
THEOREMATA. This treatise is modelled on Euclid and consists of a series of propositions and conclusions on various topics. Noone has described it as an unfinished notebook. There has been some controversy concerning the work, as passages appear to contradict Scotus' genuine writings. But these could also be explained as examples of positing impossible hypotheses in order to study what follows; for example, if univocity is not true, what does natural theology look like. My co-blogger Michael has written on this here.
