Puff m call
Dearest Puff...as an interested obsever....being Australian and ATC in UAE...
I give you DOC 4444 PANS ATM Chapter 12 12.3 ATC Phrasiologies...
a)Climb (or Descend) followed by
1) TO (level)
2) TO and maintain...
The rest of it is there if you give it a glance...
To sum up, the ATC is following ICAO standard phrasiologies...perhaps you may like to do the same??