What does a single square bracket next to a single note mean?

I just stumbled on a bit of notation in a music score, and I'm stumped as to what it means. It's a single square bracket, spanning the whole staff, to the left of a single note.

This is measure 58 of Fandango, by Padre Antonio Soler, arr. Fernand Vera, for guitar duo. The piece is in D minor.

There are also similar brackets in measures 63, 64 and 65,

as well as 98 and 125.

What does the bracket mean?

• Well... These examples also seem to suggest barres. The first three being on fret 10, for F and A on strings 3 and 2, but with the 3rd finger marking on the wrong note in those in bars 64 and 65 (one note early). The last example is just a fret 8 barre for the G and C. The fact that musical markings, barlines and notes often 'collide' here, suggests that this has not been carefully edited, and is likely to have mistakes, which is why I think the fret 4 barre was suggested in the first example... Mar 27, 2014 at 1:04
• Just to avoid any confusion: the question was originally posted with just the first musical excerpt (with no key sig.) The next two musical excerpts were then added; the comment above is a response to the these excerpts! Mar 27, 2014 at 13:46

Must simply be notation for a barre across the fourth fret, as this would also be for the subsequent G#. Admittedly, this is not the most conventional notation, but it is certainly valid.

EDIT: this kind of bracket is commonly used in bowed string (eg. violin) music, to denote double-stopped notes, which may sometimes be with the same finger, and so are an equivalent of barres. (Here, of course, the notes aren't played together though - thanks for pointing this out @Alexander Troup.)

• Apologies, I should have made this clear; the key is D minor so the B should be assumed to be flat, and on the third fret. I'm not particularly sure how to interpret the IV in light of that.
– E.P.
Mar 27, 2014 at 0:14
• Ah! Well in that case it makes no sense! I think the most obvious explanation is that there is an error in the music here. Either it is supposed to be a B natural, or the fingerings have been put in afterwards and the person putting fingerings in has not 'clocked' the Bb. I followed your link to the original, and had a very brief look, it appears this may not be conventionally edited music...? This may help to explain the error, if there is one, but of course conventionally published and edited music often has mistakes too... Sorry for not being able to be definitive. Mar 27, 2014 at 0:23
• I feel it's unlikely to be a typo; the Bb also appears in many of these other versions. I'm not sure what to make of the typesetting; it was very likely made by the arranger himself, but I do find it strange that he would include non-standard notation in his PhD thesis.
– E.P.
Mar 27, 2014 at 0:35
• Exactly, I don't think he's used non-standard notation, I think he's just made a mistake, and fingered it as though it is a B natural. The only other explanation I could think of is that the Bb is played on string 4, but a fret 4 barre is being prepared for notes in the next bar of music (I haven't looked at the next bar...) I reckon it's probably a mistake though... Mar 27, 2014 at 0:47
• Yes, the next bar does have a bar on V. I guess it can be taken to mean to bar the third fret in preparation to shift it to V. I'll look more carefully at the other occurrences to see if this fits.
– E.P.
Mar 27, 2014 at 0:56