Fair enough. It is a fingering notation of a sort, albeit a very specialized one if my memory serves. Because isn't
sul tasto and
sul ponticello a notation for where you're
bowing the note rather than where you're stopping it? I've seen that used for cello and violin scores. But the only forms I'm familiar with direct the player to
bow the strings over the fingerboard - or over the bridge.
And I was always told that the diamond shaped note meant to play a harmonic at the node specified as opposed to the natural harmonic where you put a tiny circle over the note to indicate it's a harmonic.
But that's not really the same thing as saying (for example) to play a 'normal' A note on:
- the 17th fret on the E-string
- the 12th fret on the A-string
- the 7th fret on the D-string
- or the 2nd fret on G-string
Technically you could argue they're all the "same" note. But they're really not that similar once you get beyond just the pitch.
But anyway…are there additional definitions for the 'sul' notation and that diamond shaped note on a score I'm clueless about? There's a huge number of symbols and abbreviations used in modern music notation. And I don't pretend to know all of them.