Business term (BT and BG)

Also called BT, BG, business group

EN 16931 gives every invoice field a business term identifier such as BT-1 for the invoice number, and every collection of fields a business group identifier such as BG-25 for an invoice line. Every error message you will meet is written in these codes.

BT: Business term, a single field
BG: Business group, a collection of fields
Syntax independent?: Yes. The same BT number in CII and UBL
Where you meet them: Every EN 16931 error message

Terms and groups

A BT is a single field: BT-1 is the invoice number, BT-2 the issue date, BT-5 the currency, BT-24 the specification identifier, BT-112 the total with VAT.

A BG is a container holding related terms: BG-25 is an invoice line, BG-4 the seller, BG-23 a VAT breakdown entry. Rules about cardinality talk about groups, so "at least one BG-25" is the standard's way of saying an invoice needs a line.

They are syntax independent, which is the point

BT-48 is the buyer VAT identifier whether the invoice is CII or UBL. The element names differ between the two syntaxes; the business term does not.

That is why error messages use them. A rule can be stated once and apply to both syntaxes, and a validator can report a failure without caring which shape the file arrived in.

Why it matters

Without them the rule reference is unreadable, because every rule is stated in terms of BT and BG numbers.
They are also the vocabulary to use with a software vendor, since "we are missing BT-10" is unambiguous in a way that "the reference field" is not.

Check it on your own file

Rules that require a specific field
Each one names the BT it wants, with what to supply.

Common questions

What does BT mean in an e-invoice error?: Business term: a single named field in the EN 16931 model. BT-1 is the invoice number, BT-112 the total with VAT. BG numbers are groups of fields, such as an invoice line.