BR-52

Explanation

The invoice refers to a document but doesn't give its identifier. This can be an attached or supporting document, and depending on the format also a project, a tender or lot, or the invoiced object (such as a meter or contract number). Each such reference needs an identifier, for example the document or project number.

How to fix

Ask the seller for a corrected invoice that gives the identifier for every reference, or leaves out the empty reference.