We've just released a new feature to our transposing engine to allow automatic creation of Number and Numeral chord charts.
Number charts are commonly used by studio musicians who show up and need to be ready to play a song in any key. Instead of having 12 chord charts all in different keys, you only need one number chart. Chords are replaced by numbers based on the scale of the key you are in. In D, 1=D, 2=E, 3=F# and so on. Then just by saying you are now in E, the musicians see 1 and now play E instead of D.
Numeral charts are a little different, though very similar. In a number chart, it really is as simple as replacing chords with numbers. In a numeral chart, it goes one step further. If your chord is major, the numeral is uppercase, but if the chord is minor, instead of showing the 'm', you use a lowercase numeral. In the key of C, II would be D major, but ii would be D minor.
For both numbers and numerals, if you ever use a chord or note that is not in that key, it will always be represented using flats. So in the key of C, if you have a G#, it will show as b6 or bVI instead of #5. Likewise, E/G# would be 3/b6 or III/bVI.
When creating your charts, you can enable Number or Numerals right next to the button to enable Lyrics. These files are attached to your arrangement, meaning they're available no matter what key you choose for the song. You can even preview number or numeral charts in the new chord editor.