# BT-24 Specification Identifier An identification of the specification containing the total set of rules regarding semantic content, cardinalities and business rules to which the data contained in the instance document conforms. This field identifies which invoicing specification/profile is being used (e.g., XRechnung, PEPPOL BIS). > BT-24 (Specification identifier / CustomizationID) names the standard the document conforms to. Mandatory under EN 16931. For XRechnung 3.x it must be the registered CIUS URN combining EN 16931 compliance and the XRechnung extension. Example: urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0. > > BT-24 · EN 16931 / XRechnung 3.x ## BT Reference Card Canonical EN 16931 / XRechnung facts for this business term — citable from this anchor. - **BT code**: BT-24 - **Name**: Specification Identifier - **Cardinality**: Mandatory (M) - **Business group**: BG-2 PROCESS CONTROL - **Data type**: Identifier - **Example value**: urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0 ## Quick answer An identification of the specification containing the total set of rules regarding semantic content, cardinalities and business rules to which the data contained in the instance document conforms. This field identifies which invoicing specification/profile is being used (e.g., XRechnung, PEPPOL BIS). > **Invoice basics**: Core document identifiers, dates, process identifiers, and high-level invoice context. ## In plain language An identification of the specification containing the total set of rules regarding semantic content, cardinalities and business rules to which the data contained in the instance document conforms. This field identifies which invoicing specification/profile is being used (e.g., XRechnung, PEPPOL BIS). An identification of the specification containing the total set of rules regarding semantic content, cardinalities and business rules to which the data contained in the instance document conforms. This field identifies which invoicing specification/profile is being used (e.g., XRechnung, PEPPOL BIS). Critical for electronic invoice processing as it determines which validation rules, business logic, and technical requirements apply to the invoice. Systems use this identifier to select the appropriate processing pipeline and validation schema. Essential for interoperability between different e-invoicing networks and standards. ## What you usually enter here URN (Uniform Resource Name) format following the pattern: urn:cen.eu:en16931:2017#[compliant|conformant]#[specification-specific-identifier] Typical valid values include: urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0, urn:cen.eu:en16931:2017#compliant#urn:xoev-de:kosit:standard:xrechnung_2.3, urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0, urn:cen.eu:en16931:2017#conformant#urn:fdc:peppol.eu:2017:poacc:billing:international:aunz:3.0 Mandatory for all XRechnung invoices since version 1.0. Required by EN 16931-1 standard and essential for compliance with German e-invoicing regulations and PEPPOL network requirements. ## What goes wrong often Avoid values like: XRechnung, PEPPOL, EN16931, urn:custom:billing:1.0 Relevant rule codes: BR-DE-1, PEPPOL-EN16931-R007 ## Examples in context Critical for electronic invoice processing as it determines which validation rules, business logic, and technical requirements apply to the invoice. Systems use this identifier to select the appropriate processing pipeline and validation schema. Essential for interoperability between different e-invoicing networks and standards. Mandatory for all XRechnung invoices since version 1.0. Required by EN 16931-1 standard and essential for compliance with German e-invoicing regulations and PEPPOL network requirements. ## Valid Examples - urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0 - urn:cen.eu:en16931:2017#compliant#urn:xoev-de:kosit:standard:xrechnung_2.3 - urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0 - urn:cen.eu:en16931:2017#conformant#urn:fdc:peppol.eu:2017:poacc:billing:international:aunz:3.0 ## Invalid Examples - XRechnung - PEPPOL - EN16931 - urn:custom:billing:1.0 ## Related Fields Critical for electronic invoice processing as it determines which validation rules, business logic, and technical requirements apply to the invoice. Systems use this identifier to select the appropriate processing pipeline and validation schema. Essential for interoperability between different e-invoicing networks and standards. - [BT-23 Business Process Type Identifier](/resources/xrechnung/bt-23-business-process-type-identifier) - [BT-34 Seller Electronic Address](/resources/xrechnung/bt-34-seller-electronic-address) - [BT-49 Buyer Electronic Address](/resources/xrechnung/bt-49-buyer-electronic-address) ## XML mapping and field facts Open the technical reference if you need XML paths, validator rule codes, legal wording, or schema-specific mapping details. ### Field ID: BT-24 ### Data Type: identifier ### Cardinality: 1..1 ### Requirement: Mandatory ### Max Length: 200 characters ### Since Version: XRechnung 1.0+ ## XML Implementation ### UBL 2.1 Syntax ``` /Invoice/cbc:CustomizationID ``` ### CII (UN/CEFACT) Syntax ``` /CrossIndustryInvoice/ExchangedDocumentContext/ram:GuidelineSpecifiedDocumentContextParameter/ram:ID ``` ## Validation Rules ### BR-DE-1 BR-DE-1 ### PEPPOL-EN16931-R007 PEPPOL-EN16931-R007 ## Why the standard cares about this field ### Business Context Critical for electronic invoice processing as it determines which validation rules, business logic, and technical requirements apply to the invoice. Systems use this identifier to select the appropriate processing pipeline and validation schema. Essential for interoperability between different e-invoicing networks and standards. ### Legal Requirement Mandatory for all XRechnung invoices since version 1.0. Required by EN 16931-1 standard and essential for compliance with German e-invoicing regulations and PEPPOL network requirements. ## FAQ ### What is the difference between XRechnung and PEPPOL specification identifiers? XRechnung uses "urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0" for German public administration, while PEPPOL uses "urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0" for international B2B transactions. Both are based on EN 16931-1 but have different extensions and requirements. ### How do I choose the correct specification identifier for my invoice? For invoices to German public authorities, use the XRechnung identifier. For PEPPOL network transactions, use the PEPPOL BIS identifier. The choice depends on your recipient and the network through which the invoice will be transmitted. Check with your recipient or network provider for the required specification. ### What happens if I use the wrong specification identifier? Using an incorrect specification identifier will cause validation errors and invoice rejection. The receiving system relies on this field to apply the correct validation rules. Always verify the required specification with your invoice recipient before submission. ### Are there regional variations of specification identifiers? Yes, different countries and regions may have their own CIUS (Core Invoice Usage Specification) based on EN 16931-1. For example, Australia/New Zealand uses "urn:cen.eu:en16931:2017#conformant#urn:fdc:peppol.eu:2017:poacc:billing:international:aunz:3.0". Always use the specification required by your target market. ### How does BT-24 relate to BT-23 (Business Process Type)? BT-24 defines the technical specification and validation rules, while BT-23 defines the business process context. Both are mandatory in XRechnung 3.0.1+ and work together to ensure proper invoice processing. BT-24 tells the system “how to validate”, while BT-23 tells it “what business process this supports”. ### Can I use custom specification identifiers? No, you must use standardized specification identifiers that are recognized by the receiving systems. Custom identifiers will cause validation failures. Use only officially published identifiers from recognized standards bodies like CEN, PEPPOL, or national e-invoicing authorities. ## Official sources and tools - [KoSIT Validator](https://erechnungsvalidator.service-bw.de/) - [Invoice Converter](/pdf-to-xrechnung) - [XRechnung Standard](https://xeinkauf.de/xrechnung/) - [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)