This Peppol glossary explains the key terms of Peppol and e-invoicing in Belgium in plain language. For each term, we also link to a page or tool where you can read more.
Peppol glossary: the network
Peppol
An international network and set of agreements for exchanging business documents, such as e-invoices, securely. In Belgium, it is therefore the standard channel for e-invoices between businesses. Read more in what is Peppol.
OpenPeppol
The international association that governs Peppol. It also publishes the specifications, for example Peppol BIS Billing 3.0, on peppol.org.
Access Point
The service provider that sends and receives your e-invoices via Peppol. In most cases, it is part of your accounting or invoicing software.
Four-corner model
The principle of Peppol: sender, the sender’s Access Point, the receiver’s Access Point and receiver. Because the two Access Points talk to each other, everyone can invoice everyone.
Peppol ID
The address of a business on the Peppol network. For Belgian businesses, for example, it is usually 0208 followed by the company number. Have it explained with the Peppol ID explainer. All schemes per country are in the Peppol code lists.
0208 and 9925
The two Belgian schemes for a Peppol ID: 0208 for the company number (CBE) and 9925 for the VAT number. Belgian businesses therefore register under 0208.
SML and SMP
The registers of Peppol. First, the SML knows which SMP holds a Peppol ID. Then the SMP says through which Access Point and for which documents that business is reachable. The Peppol checker also searches these registers directly.
Peppol Directory
A public list of businesses on Peppol. However, not every business appears in it, so the SML and SMP remain the most reliable source.
Peppol glossary: formats and standards
Structured e-invoice
An invoice in a structured format (XML) that software can process automatically. A PDF, in contrast, is not a structured e-invoice.
UBL
Universal Business Language, the XML standard behind Peppol invoices. You can open a UBL file with the UBL viewer, for example.
CII
Cross Industry Invoice of UN/CEFACT, the second syntax for e-invoices. You find CII in Factur-X and ZUGFeRD, among others.
EN 16931
The European standard that defines which data an e-invoice contains and how they relate. In addition, each data element has a BT number.
BT number
Business Term: the number of a data element in EN 16931, such as BT-1 for the invoice number or BT-112 for the total with VAT.
CIUS
A national or sector-specific specification of EN 16931 that makes the standard stricter, such as Peppol BIS, XRechnung or SI-UBL.
Peppol BIS Billing 3.0
The format for e-invoices and credit notes via Peppol, built on UBL 2.1 and EN 16931. As a result, it is the standard for the Belgian mandate.
Factur-X and ZUGFeRD
A hybrid e-invoice: a PDF with an XML file inside, used in France and Germany. Check one with the Factur-X validator, for instance.
Peppol glossary: validation
Validation
Checking an e-invoice for structure and rules, just as the Peppol validator does.
XSD
The XML schema that defines the structure: in other words, which elements, in which order and with which data type.
Schematron
The language for the business rules, such as mandatory fields and calculations. Moreover, each rule has a code.
Error code
The code of a rule an invoice fails, such as BR-CO-15 or PEPPOL-EN16931-R120. For each common code, see the explanation of the Peppol error codes.
Invoice Response (IMR)
A Peppol message in which the receiver reports what happens to an invoice, for example that the receiver accepted or rejected it.
Peppol glossary: legislation
E-invoicing mandate
Since 1 January 2026, VAT-registered businesses in Belgium send each other structured e-invoices. Read more about the Belgium e-invoicing mandate.
Mercurius
The Belgian platform through which e-invoices to the government arrive, also via Peppol.
E-reporting
Sending invoice data to the tax authority in near real time. Belgium plans it from 2028, so read the questions about e-reporting in time.
ViDA
VAT in the Digital Age: the European package that, among other things, provides for e-invoicing of intra-Community transactions from 2030.