This sheet presents the main features of the CEOS format, enabling you to access the products written on a medium (exabyte or CD-ROM) with this format convention.
A medium in CEOS format contains the following files :
- one volume directory file.
- one leader file.
- one data file containing all the products. If the medium is a CD-ROM, there is one file of this type per orbit and all the data files can be found on a specific CD-ROM directory.
- one null directory file ending the medium.
The first two files contain general information on the distributed products, but the products are found in the data file(s).
If the medium is an exabyte, it is then necessary to skip those two files to be able to read the products in the data file.
Data file format
The products in a data file are organised in the following format :
- one header record ( file descriptor record) of 360 bytes.
- N data records corresponding to N products. Each record consists of :
- one header of 20 bytes
- the product made of one main header (MPH), one specific header (SPH) followed by n measurements (DSR). The format is described in the product user manual.
- if necessary followed by one spare byte, so that the data record size is an even number of bytes.
Data file record sizes
The size in bytes of the data records in a data file is specific to each type of product :
- ALT.OPR : 20 + 9025 + 1 with 9025=(MPH=106 + SPH=39 + 80* DSR=111 )
- MWS.MBT : 20 + 2004 with 2004=(MPH=106 + SPH=42 + 64* DSR=29 )
- ALT.FDC : 20 + 7008 with 7008=(MPH=176 + SPH=56 + 77* DSR=88 )
- WSC.FDC : 20 + 16948 with 16948=(MPH=176 + SPH=166 + 361* DSR=46 )
- SWM.FDC : 20 + 584 with 584=(MPH=176 + SPH=260 + 1* DSR=148 )