Indicator Price Source

Most indicators read one number per bar, and which number that is, is a setting. The close is the usual default, but the open, the high, the low, or a value derived from several of them — the midpoint of the high and low, or an average of high, low and close — are ordinary alternatives. Changing the source changes every value the indicator produces, and therefore every crossing, every extreme and every divergence read from it. This is one of the reliable explanations for two people looking at the same indicator and disagreeing about it. Two charts can differ in the price source, in the period, or in whether the bars themselves are built from the bid or from some other basis, and any one of those alone is enough to move a line. There is no source that is correct in general; the useful discipline is to record which one a reading came from, so that it can be reproduced later instead of argued about.