The following FOT scheme is only for WFCs. The structure of a FOT for NFI the layout is similar but WFC and NFI will not be placed together on the same FOT. * Structure of tape: General part Science part * Contents of General part: Tape Directory Ephemeris data file Attitude data file OBT-UTC conversion data file IT-diagnostic data file TCU-HK data file (optionally Other Satellite HK data files) * Structure of Science part: Instrument file set 1 (WFC-1) Instrument file set 2 (WFC-2) * Structure of Instrument file set: Instrument Directory Initial Slew Observation set (1) ...... Initial Slew Observation set (n) Normal Observation set (1) ...... Normal Observation set (n) Final Slew Observation set (1) ..... Final Slew Observation set (n) * Contents of Observation set: Observation Directory Experiment Configuration file Instrument HK data file Science HK data file Science Event data file Directories are ASCII files that contain one line for each file or set of files that is described. - The Tape Directory describes each file on the FOT - The Instrument Directory describes each observation set of an instrument - The Observation Directory describes each file in an observation set It is possible that a FOT may comprise of more than one tape. As the distribution tapes may store 2 Megabytes splitting of FOTs is higly unlikely to occur. For a complete specification of the FOT refer to the "Mission Support Component FOT layout Document" (TPZ/GO.SDC-100/FOT-TN/SAX)