This is just a minor limitation, but I’d like to specify a negative octave in a pitch symbol. I agree that A-1 (13.75 Hz) is below the normal threshold (though humans are said to perceive sounds as low as 12 Hz under ideal conditions), however, frequencies within a negative octave may be used in a disposition as underlying fundamental note (e.g.) as I currently do in an experimental project. And it is just very convenient to specify a pitch by its symbolic name instead of frequency or cent.
Hi @kyl .You can use a MIDI note number for your case which would be “9”! You can also mix-and-match MIDI, MidiCent, and Note Names in Antescofo. Meaning, the following score is correct and corresponds to three repeating notes.
NOTE 60 1.0
NOTE 6000 1.0
NOTE C4 1.0
Note however that a 13.75Hz pitch can not be captured or recognized by any microphone/recognition algorithm precisely! If for audio detection, Antescofo will attempt to use higher harmonics for detection and depending on the context it might work! (meaning if you have octaves or harmonics of the same note all around then it’s gonna be difficult) So use at your own risk. 
In addition, you can define a macro to keep a symbolic name, like that :
@macro_def @A_1 {1460}
NOTE E4 1
NOTE @A_1 2
TRILL (E4 @A_1 E7) 3
CHORD (E4 C3 A1 @A_1) 1
It does not follow the syntax of symbolic midi note, but at least it provide a symbolic name.
Sorry, I forgot to mention that the error message comes from
@symb2midicent("A-1")
Even though one can read about very long organ pipes which are larger than 32’ I never had the occasion to hear one. I do not intend to proscribe such sounds or expect something like this to be recognized as an event. I only use it as a mere abstraction when computing the intonation of actions. As I already said, it’s not really an issue, but it would just be convenient if it was not an error.