Refer to figure.
The figure depicts a short-field take-off procedure (other than the clear area). This procedure is usually associated with an obstacle in the continued take-off area. As clearance above such obstacles is not readily associated with an accelerative procedure, as clear area procedure (runway/FATO), a procedure using a vertical climb is utilised.

A drop down to within 15 ft of the take-off surface is not deemed appropriate (as in a clear area procedure) and the required obstacle clearance height "h" is set to 35 ft (usually called ‘min-dip’). The distance to the obstacle does not need to be calculated (provided it is outside the rejected distance required), as clearance above all obstacles is provided by ensuring that helicopter does not descend below the min-dip associated with a level defined by the highest obstacle in the continued take-off area.

The helicopter has to progressively increase its speed, until it achieves V_TOSS after point B, because this speed will ensure a positive climb gradient at the end of TODRH.