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Hi Simon, Can you point me to the GRIB1 documentation for eumetsat. It seems to be a little different then the NCEP documentation for the GDS, especially for the Quasi/Thin grid processing. The problem details for a Quasi Grib1 grid from center 98 In the GDS: i know octet 5 != 255 means that this is a quasi grid. The information for the number of points is at the end of the GDS section. For NCEP grids, i get the number of parallels from the nx or ny depending on the scan mode. Then i read in the points using readUnsignedShort() for the values. This works for NCEP thin gribs, but ECMWF thin gribs give numbers in the 1000's. i know that is not correct. if i would use 3 octets to read in the values, the read would go past the length of the section. This doesn't seem correct either. i must be missing something here GDS NV = 122 octet 4 GDS PL = 33 octet 5 GDS length =520 GDS numPts = 181 GDS numPV[ 0 ] = 0 GDS numPV[ 1 ] = 0 GDS numPV[ 2 ] = 16916 GDS numPV[ 3 ] = 0 GDS numPV[ 4 ] = 16934 GDS numPV[ 5 ] = 27875 GDS numPV[ 6 ] = 16959 GDS numPV[ 7 ] = 42454 GDS numPV[ 8 ] = 16991 GDS numPV[ 9 ] = 41744 GDS numPV[ 10 ] = 17030 GDS numPV[ 11 ] = 31674 GDS numPV[ 12 ] = 17076 GDS numPV[ 13 ] = 38296 Thanks, Robb... =============================================================================== Robb Kambic Unidata Program Center Software Engineer III Univ. Corp for Atmospheric Research address@hidden WWW: http://www.unidata.ucar.edu/ ===============================================================================