Quote from ShadowedYou missed it, it's "Combat fader".
Sorry for being dense, I still can't see anything like that except under "Global" options. And of course, configuring it under global applies the same fading rules to all frames.
For each unit type, I'm looking in the main/general page, as well as in the submenu list of unit elements (eg: raid icon, combat text, etc). In the general page I only see options for disabling/copying the layout, for setting its size/pos, and for setting its border texture. In the submenu list, I only see components of the UF which would be visible if enabled, rather than behaviours such as fading.
I do have the STUF range module enabled in my addons list.