Look up a business in the public Peppol Directory — where to route an e-invoice (the BT-34/49 electronic address). ?id= (a Peppol id like 0225:992412536, or a value to search) or ?country=FR&name=. Returns { found, count, participants:[{peppolId, name, country, documentTypes[], schemes[]}] }. Unknown id → { found:false }. Directory down → 503, unbilled. Public source, 1h cache.