The HV Curve relates to take-off. See MD 600 RFM 5-8.
'Airspeed/altitude combinations to be avoided in the event of an engine failure during take off are shown in the height-velocity diagram' Quote
Agusta don't say whether it is for take off or landing. So one must assume it covers both profiles.
I don't have the B206/Enstrom/Robinson or Schweizer manual to hand. So I cant quote from them.
I've always taken it to be for both t/o and landing.