The first one, instigated also by Cavalli, involves some cuts, as well as transpositions of certain parts.
Its main purpose seems to have been to accommodate an entirely different cast; it was thus clearly designed for a different production, which nevertheless was led again by Cavalli.
In some instances, mostly in instrumental pieces, but also in choruses, the upper parts are left out entirely.
So the score clearly served as a performing score for a continuo player.
When, in 1970, Martha Clinkscale prepared her edition, she came to the conclusion that the score in its entirety represented the final draft for the Bolognese production of 1657.
This finding seems to be corroborated by the fact that a second extant score, a fair copy, preserved today in the Chigi Collection in Rome, represents exactly the same version, thus supporting the idea that this was indeed a fixed version to be produced at a certain date, and that perhaps the Roman score was prepared for use in that performance.
As Jane Glover have demonstrated, most of those scores are fair copies, made in the 1660s and 1670s, presumably for preservation purposes.
However, the majority of scores of those operas that were first performed between around 16 are autographs, seemingly preserving various stages of composition and performance in irritating complexity.Thus the initial purpose of this score was to be used by Cavalli already in the 1655 production.Apart from this first layer of alterations, however, there are at least four other layers of revisions – not three, as I wrote earlier – all made from the perspective of a continuo performer and leader of the ensemble.However, after closer inspection of the scores it must be said that the situation is much more complicated.To be able to evaluate them, one has to take into consideration what purpose these scores served.I will therefore begin by giving you a brief summary of my findings, and illustrate some aspects with new examples, considering each opera separately.