Cross-object formula spanning and syntax
Key Takeaway
A cross-object formula moves through relationship names separated by periods and must end on a field, as in Contact.Account.Name.
A cross-object formula is a formula field (or other formula) that pulls values from a related object, such as showing an account's industry on a contact record. It moves across a relationship using dot notation, so users can see related data without opening the related record.
What a cross-object formula spans
A cross-object formula spans two related objects and references merge fields on those objects. An object on the detail side of a master-detail relationship can reference fields on its master (parent) object. Cross-object formulas also work with lookup relationships.