BAe 125 Series 800
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Situational Awareness; Training / Qualification
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors; Procedure
From a cruising altitude of FL260; Toronto Center issued a clearance 'Descend to FL240; descend via the NUBER2 arrival.'  We immediately started down to FL240; and continued our descent via the arrival procedure.  Passing through FL230; the Controller asked what altitude we were going to.  We explained we were descending via the arrival; to cross ROKTO between 14;000 and 12;000. The Controller explained that the newly adopted 'descend via' phraseology in Canada does not allow us to descend below a given altitude.  After multiple inquiries; we were finally able to understand that the intention of the clearance is to descend to the given altitude and comply with the arrival restrictions.  He said there has been a lot of confusion in the first week of these new clearances; and didn't seem concerned.The 'descend via' clearance is used differently in the United States and Canada; so crews should be sure to verify with Canadian controllers what is expected of them.  Unlike the United States; a descend via clearance in Canada does not allow a descent all the way to the lowest altitude; but the specific assigned altitude.
Hawker 800 First Officer reported an altitude deviation occurred that arose from the difference in 'descend via' clearances between Canada and the United States.