Check Airman - reversing the question slightly. Phraseology outside the US is often:
"When ready, descend FL........ To be level X miles before .......XYZ"
Simple, plain, unambiguous English. So why do so many US crews (mainly Military admittedly) not realise this is a Pilots discretion descent and either power down there and then or ask "Can we have that descent at Pilots discretion sir?"