# BT-126 — Invoice line identifier

> https://billhorse.com/en/terms/bt-126/

Unique identifier of the line within the invoice, usually a simple running number (1, 2, 3 …). Mandatory for every line; serves as the anchor for queries and references.

## Where does it live in the XML?

- UBL: `cac:InvoiceLine/cbc:ID`
- CII: `ram:IncludedSupplyChainTradeLineItem/ram:AssociatedDocumentLineDocument/ram:LineID`