https://system.netsuite.com/app/help…_N2832369.html
				Using Foreign References in Formula Fields
When creating a formula field, you can reference data contained in fields on related records.
For example, if you created a custom entity field to apply to customer records, you could add a formula field that referenced a field on the employee record of the sales rep assigned to the customer.
Note: When referencing fields on other records, you are restricted to the records with search joins.  
The format for formula field references is:
{fieldOnAppliedRecord.fieldOnJoinedRecord}