Might I suggest that you check the front of the manual where acronyms are defined? I suspect that since you have an air data computer, the manual uses CAS to mean “computed” airspeed and not calibrated airspeed. Regardless, any references to airspeeds (limits, procedures, etc) unless otherwise stated will refer to the speed read off of the PFD whether that is really IAS, CAS, EAS or whatever. The only time it will likely make any difference is if you have to revert to an uncorrected (standby) airspeed gauge, but as others have pointed out the difference will only be a knot or so.