[levitate]

Interesting that in figure 2. the nine white key chords) there are keys labelled as 'H'?? it seems like they should be 'B' instead.

[ketzu]

For funny historical reasons, the english tone B is called H in some countries, especially northern and central europe. (English B-flat is called B there) Wherever that figure is from.

[kombinatorix]

Not necessarily. In Germany and probably also other parts of the world B is called H and B flat is called B.