Line Item Fields are used to define the types of data that will be stored as line item data for the records. This is typically used in situations like Invoices and Purchase Orders but can be used any time you have multiple structured data values as child elements to the main record. 

The configuration is very much the same as the Record Type Fields so refer to that section for details on field information.

Properties Specific to Line Items Fields

Total Field - The parent field with which to compare the line item total values.