Markings and symbols in Paganini violin compositions

Question

In a lot of Paganini's violin compositions, there are bolded but sometimes not bolded capital letters like A, B, and C. I look at the note that it is above and it doesn't click for me. In Nel cor piu non mi sento (1st variation), there is a marking, "A1" below the staff and under the note g-sharp, which I really don't understand. Somewhere along the ways of many compositions there is a Roman numeral with a lowercase letter, sometimes with a dot underneath that letter, below the staff. I know that the numeral means the string but what is that letter next to it for? These are really advanced markings I'd assume and I couldn't find what they are in music dictionaries and such, so I'd like to know what all these symbols mean.

^{Excerpt from score published by B. Schott & Söhne, 1829}

^{Excerpt from score published by Schott, 1909}

^{Excerpt from score published by Editio Musica Budapest, 1968}

^{Excerpt from score of 24 Caprices, op.1, publisher unknown}

Answer 1

Comparing editions, we can see that one of them marks so-called "artificial harmonics" with the open-diamond mark. The other edition has "A3" there which presumably indicates the same pitch to be played (A three octaves up), and indirectly this requires artificial harmonic compared with the written note there.

I don't recognize "Vi-" (and there's no fifth string :-) ), but perhaps it's some shorthand for the same bowing technique indicated with "saltato," i.e.

on the violin, a springing, jumping or bouncing bow, sauté (French), gesprungen (German): however, see also saltellato

With thanks as always to Dolmetsch

All the "IIa," IVa" are string-choice indicators.

Answer 2

They're probably not rehearsal letters because those are helpful only when there's more than one performer, while this is a solo.

In the half dozen editions and arrangements of Nel cor piu non mi sento that I found online, some modern, some ancient, none included such symbols. So these symbols are unlikely to be musically important. They may be peculiar to that publisher.

Edit: They mark which string to play. Here's an example.

Answer 3

Sounds like they could be rehearsal letters.

Thought I'd explain it myself, but the cited article is already pretty clear.

A rehearsal letter is a boldface letter of the alphabet in an orchestral score, and its corresponding parts, that provides the conductor, who typically leads rehearsals, with a convenient spot to begin at places other than the start of movements or pieces. Rehearsal letters are most often used in scores of the Romantic era and onwards, beginning with Louis Spohr.

Hope this helps!