I have used BayesHammer for error correction in paired end reads for an amplicon analysis experiment. Has anyone any idea about BayesHammer output? I get 3 files, one for each read and a third one called "_unpaired.00.0_0.cor.fastq". What is this third file?

In addition, in each of these file there is a label for each read "failed", "ok" or "changed:#number". What do these label mean?

Thank you all very much for your help!