All Fields available for a New Estimate with Child Records

The list and structure of a Custom URL with all possible fields, including those for Line Items that are drawn from Child Records, utilized is below. Required fields are in red. All other fields are optional.

/apex/breadwinner_ns__CreateEstimate
?originating_record={!salesforce_record_ID}
&parent_account=api_field_name__c
&custom_form=estimate_custom_form_api_field__c
&currency=estimate_currency_api_field__c
&department=estimate_department_api_field__c
&class=estimate_class_api_field__c
&location_id=estimate_location_api_field__c
&date=estimate_date_api_field__c
&expected_close_date=estimate_expected_close_date_api_field__c
&due_date=estimate_due_date_api_field__c 
&po=estimate_po_api_field__c
&memo=estimate_memo_api_field__c
&sales_rep=estimate_sales_rep_api_field__c
&child_relationship_name=child_name__r
&co_netsuite_item=netsuite_item_field__c
&co_description=description_field__c
&co_quantity=quantity_field__c
&co_rate=rate_field__c
&co_department=department_field__c
&co_class=class_field__c
&co_location_id=location_field__c
&testing=true