Custom Fields integrated with Breadwinner for NetSuite custom fields setup can be added to the parameter list when creating the custom URL button.

Note here that a Salesforce ID field has been added to NetSuite, and integrated into Salesforce using Breadwinner for NetSuite. The NetSuite field API name is custbody_sfdcid and corresponding Salesforce custom field is ncf_body_sfdcid__c.

The parameter call for cURL consists of category (co_), type (text_), netsuite field (custbody_sfdcid) and the salesforce field (Id above) which holds the value which the netsuite field will be set to.

And why is ncf_body_sfdcid__c not being used here? Simply because that is the location where the value you are setting in NetSuite is reflected back to. When the value is set in NetSuite, Breadwinner reads that value back into Salesforce Invoice record, on the Invoice object as shown above. Passing the Salesforce Opportunity ID, into the custom field in NetSuite, and showing on the custom field in Salesforce.

We designate a custom field on a transaction by starting the line of the Custom URL as &cf which is followed by the type of the custom field (in this case a picklist) followed by the API name of the NetSuite field. Here is the theoretical construction.

Button URL|&cf_type_netsuite_api_name=formula_field__c

Note above Custom Fields at the header level are prepended with cf_ and below Custom Line Item Fields are prepended with co_cf_ This denotes cf "custom field" and co_cf "child object custom field"

We designate a custom field on a line item by starting the line of the Custom URL as &co_cf which is followed by the type of the custom field (in this case a picklist) followed by the API name of the NetSuite field. Here is the theoretical construction.