UTR,
"Leave control area descending" is a level instruction - you are instructed to vacate your currently assigned level.
In the example you give above,
is that an instruction to
vacate my current level? All you have said is I can exit the control area on descent, and without restriction.
If I asked for descent, it is expected I will start descending as soon as practicable, but within one minute.
Otherwise....
If you want me to
bugger off from the level I'm presently maintaining, I would expect to hear
'DESCEND NOW' or 'DESCEND IMMEDIATELY' or be given a
'REQUIREMENT'...Which I would read-back.
There, that's all cleared up then ...
