I’m not understanding the terminology correctly here some how.

D(concert C)- Harmonic slur 2

“Keep the flow study and stay in time when changing shape.
Do not kick the air to force the upper note.”

By my understanding of what is asked for is to treat the exercise as a passive exercise.
” Keep the air steady ”
” Do not kick to force the upper note ”
Consequently the lower note is at Forte, the air remains study, and the volume decreases as the slur ascends.
There is no mention of keeping the air supported .
However on the sound track the entire exercise is at a solid Forte start to finish.
I practice it both ways and no harm done but I remain perplexed by terminology:

Keep air supported
Keep air steady
Are these terms the same or is one passive and the other active ?
Or does “keep air study ” refer to something about air flow I somehow missed along the way ?