A Universal Bill Format is an XML description of bill. It easily accommodates most complex bills and includes abstract directives for on-screen rendering. UBF acts as the structured middleman accommodating a wide variety of billing engines and bill output formats on one side. UBF Files are the core of the bill-loading and presentment process. Invoices from Billing System are normalized into UBF Files. Bill Loader parses and indexes individual invoices into invoice-parts, preserving the entire UBF. An invoice UBF part is retrieved by the Bill Presentment use case and transformed with the XSLTs to produce HTML.