There's a bewildering array of options for notating harmonics, in both standard notation and tablature. But it's particularly confusing when a notator unnecessarily mixes styles within the same piece.
Why is there no real standardization for indicating harmonics? Among other aspects, one must indicate (or default, or leave to the player's discretion):
1. which string to play the harmonic on
2. where to fret (or leave the string open)
3. where to touch (or which order of harmonic to produce)—note that this is usually indicated relative to the fret point, rather than at the actual fret, at least for artificial harmonics.
4. which hand to touch and/or pluck with
5. which main pitch to notate: where you fret, where you touch, or the pitch heard?
In addition, there are different techniques for producing harmonics (as by "tapping" or by thumb-knuckle touches), and harmonics above the 1st can be produced in at least two touch positions: a "7th fret" (i.e. 2nd) harmonic could be alternatively produced by touching near or over the sound hole.
Harmonic notation is thus a notational quagmire. For instance, using the convention followed in the second line of the sample score, where the note heads and tablature positions correspond to the touch points (as with "<12>" in tablature also), how does the notator indicate an artificial harmonic?