The grades follow the Bureau van Dijk independence indicator. A: no recorded owner holds more than 25%. B: no owner holds more than 50%, but at least one holds more than 25%. C: an owner holds more than 50%, or the company names a parent. U: we have no usable ownership record. U means unknown, not independent; keep it ticked unless you want only companies with a known record.
At the 50% line a B company whose largest stake is known to be under 50% is kept as if it were A (the EU Joint Transfer Pricing Forum suggests 50%; BvD and Germany use 25%). Tick the individual owners box to treat founder or family owned companies as independent: then only a company owner makes a company B or C.
Sources: UK private companies from the Companies House register of persons with significant control (share bands of 25 to 50, 50 to 75 and 75 to 100%; the low end is used); Japanese companies from the top 10 shareholder table and the parent company section of the annual securities report; European listed companies from the parent company tags in their ESEF report, which can only show a parent, so they are C or U, never A or B; Estonian private limited companies (OÜ) from the e-Business Register shareholder list (exact percentages); Korean companies from the largest shareholder table in the DART annual report, with the largest shareholder and its related parties counted as one owner. Danish, Swedish and Norwegian companies are all U for now. Coverage: UK about 95% graded, Japan and Korea nearly all, Estonia about 87% (AS companies keep their shareholders elsewhere, so they stay U), ESEF about one in ten flagged C, Denmark, Sweden and Norway none. Names of individual owners are never stored or shown.
The grade is a starting point. A qualified reviewer should still read the ownership and related-party notes in each annual report.