The primary element in a match rule that compares two match candidates.

As you saw in the preceding sections, the match rule contains various key elements. The primary element, usually positioned in a JSON after the comparator and match token classes, is the rule’s comparison formula. Depending on the rule type you choose (automatic, suspect, <custom>, or relevance_based), it will be a boolean or arithmetic expression that defines how two match candidates should be compared for similarity. The rule will use Comparison Operators and Helper Operators as the key components of the expression.