Defines a set of rules that will automatically calculate values inside the data set. Rules are evaluated until all conditions are met while employing a forward-chaining method (http://en.wikipedia.org/wiki/Forward_chaining).
Each rule is a way to compute a field in an entity within the data structure (using the XPath rule) or to compute more fields within an entity (using the XSL rule). The entity on which the rule operates is called the rule entity.
Rules aren’t run for all the rows at once. They are run for each row independently.
Rules are fed every time by the slice of the whole data structure - sliced by the actual row in an entity the rule is built on (rule entity). So that:
- All the parent entities are present, but the rows are limited - only the parent rows of the rule entity row up to the ROOT are present.
- Sibling entities (of rule entity) are not present.
- The Rule entity has only a row on which the rule operates.
- All the child entities are present with all the rows.