A tag rule defines certain criteria that determines if one or more tags and/or relations are implied on an object. In addition to the Condition property, tag rules contain three definition lists: Tag List, Tag Group List, and Relation List.

When a “tag-able” object is evaluated, the process determines if the object meets the criteria specified in the Condition property of each tag rule. If the criteria is met, it will return a tag (or relation, or tag group) with the value set (if other than a Marker tag). If the criteria is not met, then the implied tag does not apply and a null value is returned. Eventually, the results from the tag rules in all of the smart tag dictionaries in the station are merged to form the complete set of implied tags and implied relations for an object.

The Validity slot of a definition (TagInfo, RelationInfo, or TagGroupInfo) is not evaluated in a tag rule or in a tag group definition. It is only evaluated in the Tag Definitions of a tag dictionary.

Any definition (tag, tag group, or relation) that exists in a Tag Rule or Tag Group Definition is required to have a corresponding definition in the main lists of the tag dictionary (Tag Definitions, Tag Group Definitions, Relations Definitions).

Added scoped tag rules provide a means of focusing tag rule evaluation in specific areas of the station tree.