Why Decifra does not accept the symbol 10 (for example, C7/9/10) ?
R. Because it is uncommon and unnecessary, as the 10ths are equivalente to the thirds. Thirds are accepted, although again unnecessarily (their presence is implicitly indicated by the major and minor classes of chords, and their absence is also shown by the sus symbol). In the same way, the 5th is not usually indicated. For example, you don’t need to write C3/5 to indicate a C major, nor a C3b/5 to characterize a C minor. Just write C or Cm, as usual.
