CMYK - Working Space
Making your choice of CMYK Working Space isn't that different to RGB
except of the list of available colour profiles is rather different.
Again, having "Advanced Mode" activated gives us a more
extensive list.

As mentioned above, the choice for you make is pretty much irrelevant
if using a consumer class inkjet printer. In my case I just picked US. Web
Coated, but notice that we can also pick the old Photoshop 4 or 5 default
CMYK options, the ColorSync settings (Mac only), or even customise our
own settings as shown below.

Example - Customised CMYK
Remember the above screen grab is an example of a customised setup,
don't even consider trying to configure your setup to match it.
Greyscale - Working Space
The Greyscale Working Space has probably undergone the biggest change
from Photoshop 5 days. We now have access to two gamma settings, a
series of five pre-set dot gain curves, the ColorSync "Grey Work
Space" (Mac only) and the ability to customise the dot gain to
our own requirements. This latter option is of particular significance
to users of Jon Cones Piezography Black and White printing
system (to be discussed in a separate essay). The screen grabs below
show the various options and a typical customised "Dot Gain"
curve.

Please note that if you choose to use a "Custom Gamma"
or "Dot Gain" this will be the Working Space listed in
the Grey Working Space pop-up menu.

Example - Customised Dot Gain
Curve
One very important point, and one not to be missed regarding
Greyscale. Greyscale is no longer tied to the CMYK setup! This is why some
legacy greyscale documents might not look quite the same as they did in
Photoshop 5.x
Spot - Working Space
The Spot pop-up menu is broadly similar to the greyscale, but
for spot colours. The options that we find include a series of five
pre-set "dot gain" options and the facility for
customising the "dot gain" curve if required. In my
case I simply selected the standard 20% option.