# Glossary Source: https://developer.avalara.com/products/e-invoicing/integration-guides/elr/elr-glossary/ Guide: E-Invoicing and Live Reporting # Glossary Before continuing, be sure to review the terms in this section, which are provided to help you better understand E-Invoicing and some of the abbreviations used in this guide: **Terms** **Description** 4-Corner e-invoicing model Under the four-corner model, there are four corners underpinning the issue, exchange, and receipt of e-invoices, namely C1 (the Sender of the Invoice) who sends an e-invoice to C2 (its service provider), who sends the e-invoice to C3 (its customer’s service provider), who in turn sends the invoice to C4 (the Customer – the ultimate receiver of the e-invoice). The senders and receivers of e-invoices (C1 and C4) utilize their own choice of system/software. B2B Business-to-Business B2C Business-to-Consumer B2G Business-to-Government CII CII is the abbreviation for Cross Industry Invoice. It's a technical specification that is used to create a message syntax that can be exchanged globally between trading partners. It was developed with input from Governments and Tax Authorities, including the UK’s HMRC. CIUS CIUS is the abbreviation for Core Invoice Usage Specification. It is a specification and set of instructions that provides a business with detailed guidance, explanations, examples, and business rules related to the actual implementation and use of structured information elements present in a core invoice model. A CIUS is generally implemented at a national level, setting out specific rules and restrictions. Code lists Code lists that have been standardized within Eurostat. This means that unique concepts defined by single identifiers (codes) are used across different statistical domains. Creditor The party to whom a debt is owed. The party that claims the payment and is responsible for resolving billing issues and arranging settlement. The party that sends the invoice or credit note. Also known as invoice issuer, accounts receivable, or seller. Customer The customer is the legal person or organization who is in demand of a product or service. Examples of customer roles: buyer, consignee, debtor, contracting authority. Debtor The party that owes a debt. The party responsible for making settlement relating to a purchase. The party that receives the invoice or credit note. Also known as invoice, accounts payable, or buyer. EDI EDI (Electronic Data Interchange) is the technical term for the standardized exchange of digital information between two parties via their ERP, accounting or billing system. EN 16931 [EN 16931](https://ec.europa.eu/digital-building-blocks/wikis/display/DIGITAL/EN+16931+compliance) is the European standard on e-invoicing that was developed and published by the European Committee for Standardization (CEN), at the request of the European Commission. There are two main parts to the standard, a semantic data model and the two mandatory syntaxes that comply with the standard i.e., UBL and CII. G2C Government-to-Citizen G2G Government-to-Government Hybrid PDF A hybrid e-invoice combines both a human-readable PDF for users and machine readable XML data for process automation. Peppol Pan-European Public Procurement Online, or Peppol, was originally created to set common standards for public procurement across the EU (B2G). However, today it's both a delivery network and standard for e-invoicing (and other procurement processes). Peppol meets the European e-invoicing standard (EN16931) through its [Peppol BIS Billing 3.0 specifications](https://docs.peppol.eu/poacc/billing/3.0/bis/). The Peppol network is accessed through access points and certified providers and is therefore a good example of the 4-Corner e-invoicing model. Schema A schema is a formal way of describing an XML, setting out the detailed constraints on an XML document’s logical structure. Tax authorities will generally define a specific schema for an e-invoice or digital reporting requirement. Semantic Data Model A Semantic Data Model is a structured and logically interrelated set of terms and their meanings that specify the core elements of an electronic invoice. In effect, this defines the content requirements of an e-invoice, the data elements that need to be included, and what they mean (like a data dictionary). Supplier The supplier is the legal person or organization who provides a product or service. Syntax A syntax is the electronic message structure. Another way of looking at a syntax is that it is the machine-readable language used to represent the required data elements. Correct deployment of the format allows for automated processing of the content. UBL is the standard XML syntax for electronic business documents, including e-invoices. A second common XML syntax is CII. UBL [UBL](https://docs.oasis-open.org/ubl/os-UBL-2.1/UBL-2.1.html) is the abbreviation for Universal Business Language. It's a technical specification and standard XML syntax that is the result of international collaboration to define a library of standard electronic XML business documents such as e-invoices. XML XML is the abbreviation for Extensible Markup Language, and it's a language and file format for the storing, transmitting, and reconstructing of data.