How about this:
ATC: ABC123 fly present heading for radar vectors etc.
ACFT: present heading 150 degrees for vectors ABC123.
I also do not like to use the word "maintain" although if it must be used what about the following "climb to and maintain FLXXX"
Just my thoughts from the west side of the pond.
Cheers
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Keep the shiny side up and the dirty side down.
Canuck Av8r
ICQ 26305263