... The quality control system calibrates the VLT instruments and monitors the quality of data. ... The calibration plan defines the observation, calibration procedures and data needed to achieve the specified quality level defined by Instrument Scientist. ... A concept inherent to quality control is the distributed system: it allows several on-line users to simultaneously do some analytical processing of distributed data. ... Documentation (version 1.0) . ... Library version 1.0 (9/12/96) . ...