Zone (supply and demand)

An area rather than a level. Where support and resistance are conventionally drawn as lines through prior turning points, a zone is drawn as a band with a top and a bottom, on the reasoning that buying and selling interest sits across a range of prices rather than at one of them. A demand zone lies below the current price and names an area where buying previously overwhelmed selling; a supply zone lies above it and names the reverse. The vocabulary comes from retail chart teaching rather than from any exchange, regulator or vendor, and no data provider publishes zones.

Identification follows a common recipe, which is a convention and not a measurement. The chartist looks back for a short cluster of small overlapping bars, called the base, from which price departed unusually quickly, and draws the band across that cluster, most often from the open or close of the base to the extreme of its wicks. The speed of the departure is what the recipe treats as the evidence: an area price crawled away from is held to say little, while an area it left in a few bars is held to say that one side was filled and the other was not. Freshness is the second convention, the idea being that a zone price has already returned to has had its resting interest consumed.

The mechanism claimed for it cannot be checked. The whole argument rests on orders left unfilled at those prices, and in a market dealt over the counter there is no consolidated book to inspect, so what is offered as an explanation of order flow is in practice an inference from the shape of the bars. Practitioners divide on this. One camp treats zones as a plain-language restatement of where volatility and volume clustered, which is a description nobody disputes; another treats them as evidence about resting liquidity, which is a claim the available data cannot settle either way.

The measurement problem is the trip. A band is wide by construction, so a zone can be described as having held over a range where a line would plainly have failed, and two chartists drawing the same base with different edge conventions produce two different zones from identical bars. That width also makes retrospective counting close to meaningless, because the rule being tested was never written down precisely enough to test. The neighbouring terms are worth keeping apart: a key level is a single price, a range is the band price is currently contained inside, and a zone is a band price left behind and may or may not revisit.