The quick answer
Create a transaction body field with a compatible text type, select Sale on Applies To, and set Source List to Customer and Source From to the customer's field. Save the definition, then select a customer on a sales-order form that shows the field. In this example, Service territory changes from blank to Coastal, then to Inland when the customer changes.
Before you start
The customer field already exists as Free-Form Text and applies to customers. Cedar Point Service holds Coastal; Alder Bay Service holds Inland. Confirm those source values before testing the transaction field.
Use a role that can customize transaction body fields and read the source field. The example uses Administrator. Your sales-order form must show the transaction field, and field access must permit the role to see it. Main alone does not override a form that hides the field.
Field locations and selector controls vary by account and form. This walkthrough uses a dropdown for Source From; your account may show a lookup. Source List choices also depend on the transaction and related record.
Alex Morgan and Example Supply Co. are fictional example data. The field definition is saved during the walkthrough. The sales order remains unsaved throughout the test.
1. Create the body field
Open Customization > Lists, Records, & Fields > Transaction Body Fields > New. Enter Service territory as Label and _service_territory as ID.
Select Free-Form Text and keep Store Value checked. This example uses Free-Form Text for both fields. Source and target types must be compatible; other types may need a different configuration.
On Applies To, select Sale. This makes the body field available to sales transaction categories; it does not restrict it to sales orders or create a field on individual item lines.
2. Choose the customer source
Open Sourcing & Filtering. Set Source List to Customer.
Set Source From to Service territory. Source List chooses the related record; Source From chooses the field on that record. If the customer field is missing, check its type, customer applicability and role access.
3. Set the display
Open Display. Set Subtab to Main and retain Normal as Display Type. Use a sales-order form that shows the field. Do not use Hidden for this sourcing configuration.
4. Save the field definition
Click Save. Find Service territory in Transaction Body Fields. NetSuite prefixes the typed suffix with custbody. Verify the resulting full ID; the example is custbody_service_territory.
Confirm the row shows Main under Tab and Service territory under Source. This verifies the saved field definition.
5. Test two customers
Open Transactions > Sales > Enter Sales Orders. Confirm the intended form is selected and shows the field for your role. Customer and Service territory should initially be blank. Select Cedar Point Service and let sourcing finish.
Service territory becomes Coastal without entering text into that field.
Change Customer to Alder Bay Service on the same draft.
Service territory changes to Inland. Leave the order unsaved. The two selections confirm entry-time sourcing in this browser form; they do not test saving a transaction, later customer-master edits, imports or integrations.
Common questions
What is the difference between Source List and Source From?
Source List identifies the related record reference. Source From identifies a field on that record. Here, Customer supplies the record and Service territory supplies the text.
Why is the customer field missing from Source From?
Check that the source field exists, applies to customers, is readable by the role and has a compatible type. The related-record reference and available fields can vary by transaction and account.
Why does the transaction field not appear on my sales order?
Check Sale applicability, the field's subtab and display settings, the transaction form's field visibility and the role's field access. Main does not force a custom form to show the field.
Will changing the customer update the sourced value?
The two selections in this browser-entry example source the corresponding territory. Test other forms, entry channels and customizations separately before relying on the same behavior there.
Does Store Value keep saved orders synchronized with customer-master changes?
Store Value makes the transaction field hold its own value. It does not by itself keep existing orders synchronized with later customer-master edits. This walkthrough leaves the order unsaved; test saved-order edits, re-sourcing and customizations separately.
Does Sale limit the field to sales orders?
Sale makes the field available to sales transaction categories. It does not limit the field to sales orders. Review the forms and transaction types where the field should appear.
Supporting reference
Oracle's custom field sourcing guidance explains Source List, Source From and display constraints. Test the configuration on the forms and entry channels your team uses.