everything that is alive, has senses and a brain (or the corresponding organ) capable of translating sensory inputs into experiences, is equipped with katastematic pleasure at birth. This pleasure is, simply put, background noise to life.
As such, katastematic pleasure has nothing to do with intensity, location and duration. These can be descriptors of kinetic pleasures. If one really wants to apply these descriptors to human katastematic pleasure, they would look something like this:
intensity: subjective and unquantifiablelocation: somewhere between one's ears
duration: lifespan
This is interesting, but in pondering it, I keep coming back to Epicurus' wording. To paraphrase: the healthy functioning of the body and lack of disturbance in the mind. But, to me, this mustn't be considered simply background noise, and it still consists of intensity, location and duration.
For something to be a pleasure, by definition it must be felt. With this in mind, a "background state" could easily be misconstrued (and typically is, outside of this forum) as a "neutral state", even though I don't think that's what you're saying TauPhi .
By being in either the body or the mind, these felt pleasures have a location. They have duration, which can be anything from fleeting to long lasting. (Think of times when your body feels really great or your mind is really clear. For me, these times are fleeting. If they're long lasting for you, tell me how you do it!) And they have varying intensities, depending on the particular situation.
So apparently where this is leading me is to the conclusion that ataraxia and aponia are most likely the katastematic pleasures. But they are like all other pleasures in that they vary in intensity, location and duration. If there is anything that categorizes them as separate from other pleasures (notice that I studiously didn't say "makes them special") it's the breadth of their locations: aponia being throughout the body at a given moment and ataraxia being throughout the mind at a given moment. Unless, of course, you're a god. (Which kind of sounds similar to a Stoic sage as I write this... but I digress.)