This is not the final website. It is a demo of the real tool working, made for Y Combinator.
AxisRemedy

15-005 A given cell’s header cannot be unambiguously determined.

The header cells of a cell cannot be determined unambiguously.

Checkpoint
15: Tables
ISO 14289-1 (PDF/UA-1) clause
7.5-2
Test type in the protocol
Needs a human judgement
Applies to
A single object

How AxisRemedy handles it

Left for you. A person has to judge this one. AxisRemedy does not test it; the report lists it as left for you.