Every response carries the source filing, the date it was filed, and the date we observed it. If a field cannot be traced to a document, it is not in the response.
The core call. Give it tickers you cover; get back what you do not.
filed is when it became true. observed is when it became knowable to us. Backtests should use the second. Most relationship datasets only keep the first, which is how look-ahead bias gets in.