That means it probably is a fly-by-wire throttle. Basically 'fly-by-wire' is a term applied to a system where the control of the throttle is not direct from the throttle pedal but instead via the ECU. In a fly-by-wire system when the driver presses the gas pedal a signal is sent from the gas pedal module to the Electronic Control Unit. The ECU then decides how far to open the throttle on the basis of engine speed, load, air temperature etc and sends the appropriate signal to the (dreaded) Throttle Control Module, which is basically a small motor with a pair of sensors attached (that monitor the throttle position and report back to the ECU to confirm the throttle has opened the prescribed amount). On older cars (pre late 98 I believe) the throttle is opened in the good old reliable cable attached from the throttle pedal direct to the throttle method. In late 98 and onwards Volvo introduced the new system as it allows better control of the throttle, improving emmissions, power and economy (allegedly!). You may have seen a lot of posts regarding the ETS light issues that beset later Volvos... this is down to a common failure of the Throttle Control Module (around $1000 to fix). If you aren't sure if yours is a fly-by-wire then turn on the ignition, look at the warning lights and if you have an ETS light then it is a fbw model...

Hope that explained it clearly....

Alastair