9.2.3 Documents which refer to a non-written disclosure 

Where a document cited in the search report refers to a non-written disclosure (e.g. conference proceedings), it is labelled with the letter "O'' (see B‑VI, 2). For oral disclosures that took place at an officially recognised exhibition (Art. 55(1)(b)), see B‑VI, 5.5. The document category "O" is always accompanied by one of the letters explained in B‑X, 9.2.1 and B-X, 9.2.2 to indicate its level of relevance. So e.g. "O, X", "O, Y" or "O, A".