How would you spell this chord?

Bb7sus4, don't let the fact that both the 4th and the 3rd are played in the chord deceive you; in fact, Herbie Hancock often used 7sus4 chords while also playing the third in the upper register. Even Mark Levine in the "Jazz piano book" states that the 7sus4 chord often appears without the third, but sometimes the third is present. Playing in the upper register, the major third sounds a bit like a tension within a normal 7sus4 chord

Bb711, I am also tempted like Leo to consider it a SUS4, but the third should give way to the fourth in a SUS, namely the Eb. To me, it is just a type of voicing for an eleventh chord.

I would also lean towards a sus chord with the third (tenth) used as tension; the problem is whether there is a way to notationally symbolise it. Mintzer sometimes symbols it as 11, but that is a somewhat ambiguous notation: some interpret it as sus, others as a 7 with the eleventh in the melody (like Bb, D, F, Ab, C, Eb).

The doubt arose from an entrance exam questionnaire for the Paris Conservatory, which a student of mine showed me; there were several chords that were a bit awkward to define, and the impression was that they wanted a notation that described the chord in as much detail as possible.

The question I wanted to ask lies precisely in the function of that chord. You are talking about notes and not an chord, so if the chord were in the standard... then it must be Bb7sus4. If the answer were no, eh..eh., what would be the note of the standard being harmonized; perhaps it turns out that the chord could even be something else.

Take away the "melody" note and we will have a reasonably certain answer

It was a series of chords not connected to each other, if I find it again I will post it.

If they were the notes of the chord, I would chord it as Bb711

Bbsus17, Chick Corea also uses it in a famous harmonization of "Easy to love"; the principle is that the third placed so far from the root (specifically at a distance of a 17th) loses its meaning as a third, becoming almost a tension; I agree with Leoravera.

From the initial notes, I am unable to determine that the third is "so far away"; I ask, couldn't it be, for example, at a tenth's distance?

But assuming that the third is far away, doesn't SUS specifically replace the third?

The arrangement was given by Dr Jellyfish: Bb Eb Ab F (a sixth away from Ab) and D (a sixth away from F and therefore a 17th away from Bb).

I understood the reasoning that excludes the Re being the third and the Mib being the eleventh.

However, a seventeenth is practically a 9-note chord; besides not being a simple notation, as a coding it seems to me to go beyond the fifteenth, which are the classic 2 overlapping sevenths.

It probably wouldn't be bad to know the context in which the chord is used ... always according to me, obviously.

The suffix 17 indicates precisely the fact that, being so far from the tonic, the third can lose its modal connotation and almost assume the role of a tension. The fourth, on the other hand, Eb, in this arrangement is close to the tonic, reinforcing the concept that the chord, according to the author's intentions, could be understood as a sus.