This part of the guide refers to the clouds tab of the Atmosphere editor. It is also related to three other pages of reference material which show what each of the cloud types looks like when rendered in each of the three models they are available in.
See the Guides page for these reference guides
You will notice that the cloud tab with the spectral mode has a few more options than the standard and volumetric models, as such the spectral model will be covered later in the guide in part 7.
The cloud animation area will be largely ignored for this guide.

