The flightdata from the WFC instruments are telemetered to the ground and stored in the Science Data Centre (SDC). The telemetry consists of a stream of packets containing the data as produced by the instrument. The layout and contents of the packets for the WFCs are fully described in the SAX Wide Field Camera User Manual (SRON document SRU/SAX/PR-15 or ALENIA document SX-MA-AI-019 SAX USER'S MANUAL Volume 11) At the SDC this data is processed and results in the production of Final Observation Tapes (FOT) which are shipped to the requesters of the data either for the WFCs or for the Narrow Field Cameras (NFI) Not only the data received when the satellite is locked on the target (Normal Observation) but also during the time it is slewing from the previous target (Initial Slew) and the time it is slewing to the next target (Final Slew) is stored on the FOT. Here we only discuss the FOT of the WFCs which contains all information of the Wide Field Camera (WFCs) recorded during one Observing Period (OP). Although during such a period a fixed part of the sky will be observed it is very likely to be split up in several Observations mostly resulting from instrument mode changes by commanding. This may occur as a reaction on earth eclipses and passes through radiation belts or otherwise. Each such Observation results in a specific set of data files. Such a set consists always of the following files: a. Experiment Configuration datafile (EXCONF) b. Instrument Housekeeping datafile (HKD000) c. Science Housekeeping datafile (ENG000) d. Science Event datafile from one of the following modes: Normal Mode (DIR001) High Time Resolution Mode (DIR002) Background Analysis Mode (DIR003) Diagnostic Reduced Mode (DIR004) Diagnostic Extended Mode (DIR005) Test Mode (TST000) In the SDC the telemetry packets of DIR001 and DIR002 and ENG000 are reformatted while the other modes are passed on as the were transmitted by the satellite. FOTs can be identified in several ways: - By Observation Period number It is a number uniquely assigned to a certain time that the instrument was observing a pre-assigned target. It must be realised that it is possible that several FOTs can be produced over the same OP. This may happen when improved auxiliary data has come available or when FOTs are requested anew. - By FOT number This number is uniquely assigned to each FOT and is stored in the first record of a FOT - By the startdate and time of an Observation Period Starttime Also these times are to found in the first record of a FOT. N.B. Throughout this document the OP-number is used to specify a FOT.