Neutral second

Neutral seconds are intervals with a size in between a whole tone and a semitone. They are one of the most distinctive-sounding yet versatile xenharmonic intervals, which makes them highly valuable.

Function

The small step of antidiatonic is a neutral second, which functions similar to both a whole tone and semitone.

Porcupine neutral seconds are larger neutral seconds most commonly between 2\15 and 3\22 which, consistent with Porcupine temperament, split a sharp 6/5 in half and a flat 4/3 into thirds. This functionally makes them a very flat minor whole tone, and are thus an easy way to make otherwise uninteresting progressions sound xenharmonic.

Categorization

Neutral seconds are generally considered to be between 1\9 and 1\7, being half of some sort of minor third. If semifourths are included, they can be as narrow as 1\10.

Ground's Neutral Second Categorization System

This is going to need a huge table import.