turbo 60mm throttle body q's

so I picked up a turbo 1g throttle body and noticed it had 4 nipples for vacuum instead
of 3

so here it is

http://i1217.photobucket.com/albums/...203_025915.jpg

here are the nipples

http://i1217.photobucket.com/albums/...203_025720.jpg
http://i1217.photobucket.com/albums/...203_025753.jpg

I assume that the fourth nipple can be used for the wastegate?

any info would be great

also the so often mentioned biss screw is this right

http://i1217.photobucket.com/albums/...203_025838.jpg

and could someone explain what biss stands for

I'll try to explain. Sorry if the names of the systems will sound to you not familiar. Model up to the year 2000. Nipples A1, A2,P - the entrance in front of the throttle. Nipple E - input after the throttle. Model after the year 2000- nipple P, also after the throttle. A1 - Management of the electromagnetic valve of the system of recirculation of exhaust gases (egr). E - Output control solenoid valve recirculation(egr). P - Solenoid valve canister purge. A2 - Management of the electromagnetic valve of pressure boost.

Screw BISS - factory adjusting idle. This screw seal, adjusting the screw is not recommended. In your photo the seal is removed. When you set the throttle on the engine, you should configure the idle correctly.