Sweep EQ question(tascam 488)

Ok,bear with me now
The spec's read
High shelving 10Khz +/-12db
Mid 250hz to 5Khz +/-12db
Low shelving 100hz +/- 12db
Frequency response 20hz to 22khz
Now my question is,is the frequecy response my whole possible bandwidth?
For example:the high shelving Starts at 10khz to 22khz?and the low shelving Starts at 20hz to 100hz?
I get the mid.I have two controls for that.I it seems from the mid is I can set which freq I want to boost or cut from 250hz to 5Khz.
What I don't quite grasp is the single high and single low.
If I crank up(or down) the high+/- 12db,what frequency am I boosting(or cutting)?
Same with the lows.
Does anyone know the Q's listed for this EQ?
It was not listed in the spec's
Hope I was clear enough .
Thanks for the help.

I've got the Tascam 424 which uses the same EQ as your 488. Boosting the highs will raise the level of everything above 10 Khz, and cutting them will lower everything above 10Khz. Same with the low's, only it cuts and boosts everything below 100Hz. I'm not sure what the Q width is though.

Hey thanks for the help.I also have the 424.Nice to see not everyone has gone digital.