Quality control outputs are produced into PAF files. A PAF file is a PArameter File containing formatted ASCII data looking like a FITS header. They are made so that human beings can read them easily, and so that they can also be parsed by software means.
Keywords belonging to the realm of quality control products are currently being defined in a dictionary for later acceptance by the DICB board at ESO. Expect changes in the months following the release of this document.
See the chapter dedicated to ISAAC pipeline products for a full description of all possible output keywords.