sorry about the delay in replying to your questions:
The colors on the tuning chart tell you the absolute pitch of the note, i.e. in which octave it is to be found on a piano keyboard. If you scroll down to the bottom of the page you will see a heading “signs and symbols” on the right hand side, and 2 rows of colored squares below it. The upper row uses the ISO pitch designation, where each octave is numbered. The lower row shows the German system. As the site runs in both languages, we employ the color coding so that users of both systems can understand it.
C4, the blow note in channel 1 of a harp in C, is middle C on the piano. In German musical terminology, the note B is referred to as H, so we use the symbol B(H) to designate this note.
I hope you’re enjoying playing your Special 20, it’s a great harp,