4.1 SAX Final Observation Tape Layout

A FOT is physically either a DAT 4mm cassette, or an Hexabyte 8mm cassette, or a 1.2 inch tape reel (or even more than one in case of multivolume FOTs).

The FOT is a sequence of tape files, each one separated by a tape mark, and terminated by a double tape mark.

Physically each file is in "fixed blocked" format, i.e. all tape blocks are of the same length (in a file; this length may differ from one file to another) with the exception of the last block which may be shorter. All block lengths are multiple of a common logical record length.
The filing process is essentially the unblocking and the reconstruction of disk files with the original record lengths.

Top level FOT layout

The logical structure of a FOT is a sequence of files and file groups ordered in a topdown hierarchy as follows :

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sax.iasf-milano.inaf.it/Xashelp/fotfile.1.html :: original creation 2002 Sep 04 17:37:46 CEST :: last edit 2002 Sep 04 17:37:46 CEST