wm-icons theme provides icon definitions for the following aliases:
  * norm - iconified windows
  * mini - mini-icons used in the titles, WindowList, app icon managers.
  * menu - icons used in menus
  * bar  - icons, which can be used in modules
  * more...

Note that currently the definition part of this theme is moved to options.
fvwm-themes includes 2 icon sets from wm-icons: 16x16-general, 48x48-general.

You should have wm-icons package installed to actually change icon sets.
The version 0.2.6 includes 15 themed icon sets, 60 pixmaps in each.
See http://wm-icons.dhs.org/ for more details.

