The document discusses out-of-specification (OOS) test results and the process for investigating them. OOS results occur when analytical results fall outside established specification ranges. There are guidelines from organizations like MHRA, CDER, and PIC/S for handling OOS products. Investigations of OOS results involve a Phase I laboratory investigation and may proceed to Phase II and III manufacturing investigations. The goal is to determine the root cause and decide if corrective actions can resolve the issue or if the batch must be rejected.