where is ref level on the realitine scale

If you're talking about digital level, ref is full-scale -- i.e. the highest. Anthing else will be termed in negative (as in "-3db" etc). Accordingly, the lowest scale on, say, 16 bit should be s/where around -96db.
Sorry if I misunderstood yr question

For magnetic tape it is 0 VU referenced at 250nWb/m (nanowebers per meter) input
For phono cartdrige output (mV) it is at some reference velocity in cm/s (the actual number escapes me)
For speaker output (dBspl @ 1M) it is at 1mW/8ohms reference input
I hope this helps.

In THX parlance "reference level" means a couple of different things. The level calibration of the white noise generator for surround level is 85db for THX movie theaters. For Home THX, it is usually specified as 75db. Using your trusty Radio Shack analog SPL and your internal or external white noise generator, you set all your speaker levels to 75db. When people speak of playing a THX system at "reference level" that is the 0db setting on your controller after the levels have been calibrated. Movie dialog should be at about 75db and peak levels can be as high as 105db. Hope this helps.

thanks everybody, and sorry for rushing through the question.
i am talking about ref level while watching a home theater. i dont know if anybody has experance with onkyo receivers but it came with a mic for speaker setup. it played loud white noise from all speakers twice and gave feedback and option to set. it said i had no sub. does that mean i need to turn it up? the reciever set the 3 front speakers +3 dB to keep up with the effeciant rear ch (96 dBW). would that make -3 my ref level? also can you really turn it up that loud without damage?

system:

onkyo tx sr 702
carver tfm-15 front 2 ch
nht 2.5i main (86 dBW)
polk rti38 center (temp)
cerwin vega te 30 rear (96 dBW)

thanks again everybody

forgot to include sub, klipsch ksw12, in my system. also typo on the cerwin vega RE 30. all cables and cords are decent quality. onkyo dv-cp702 dvd changer.

BTW, the re-30"s (4 ohms) rock when connected to the carver 100 wpc.