The value-area is built outward from the point-of-control until about 70 percent of volume or TPO count is enclosed. Its top edge is the value area high.
Traders treat it as the upper boundary of accepted prices. In balanced conditions price rotates between the value area high and low, making the edges natural fade points; acceptance above it, meaning sustained trade rather than a poke, suggests the market is seeking higher value.
The 70 percent figure comes from the first standard deviation of a normal distribution, which real profiles rarely are. The boundary is a useful convention, not a statistically rigorous threshold, and it should be treated as a zone rather than a precise price.
Related: value-area-low, value-area, point-of-control, market-profile, balance-area