Format Magic Numbers

Macros
#define	NEP_MAGIC_GEOTIFF_STANDARD   "II*"
#define	NEP_MAGIC_GEOTIFF_BIGTIFF   "II+"
#define	NEP_MAGIC_CDF   "\xCD\xF3\x00\x01"
#define	NEP_MAGIC_GRIB2   "GRIB"
#define	NEP_MAGIC_FITS   "SIMPLE"
#define	NEP_MAGIC_PDS4   "<?xml"
#define	NEP_MAGIC_DICOM   "DICM"
#define	NEP_MAGIC_PDB   "HEADER"
#define	NEP_MAGIC_MMCIF   "data_"

Detailed Description

Each NEP format handler is identified by a short byte sequence (magic number) at the start of the file. NetCDF-C compares the first bytes of any file opened with nc_open() against each registered magic string to select the correct UDF handler. All magic strings are null-terminated C strings except NEP_MAGIC_CDF, which contains embedded null bytes and must be matched by length.

Macro	Value	Format	Notes
NEP_MAGIC_GEOTIFF_STANDARD	"II*"	GeoTIFF standard TIFF	Little-endian TIFF byte-order mark
NEP_MAGIC_GEOTIFF_BIGTIFF	"II+"	GeoTIFF BigTIFF	Little-endian BigTIFF marker
NEP_MAGIC_GRIB2	"GRIB"	GRIB2	All GRIB editions share this magic
NEP_MAGIC_FITS	"SIMPLE"	FITS	First 6 bytes of every FITS file
NEP_MAGIC_CDF	\xCD\xF3\x00\x01	NASA CDF	4-byte binary signature
NEP_MAGIC_PDS4	"<?xml"	PDS4	XML declaration; namespace checked
NEP_MAGIC_DICOM	"DICM"	DICOM	4-byte prefix at byte offset 128
NEP_MAGIC_PDB	"HEADER"	Legacy PDB	First record name of the file
NEP_MAGIC_MMCIF	"data_"	PDBx/mmCIF	First token of every CIF data block

Macro Definition Documentation

NEP_MAGIC_CDF

#define NEP_MAGIC_CDF   "\xCD\xF3\x00\x01"

NASA CDF magic number: 0xCDF30001

NEP_MAGIC_DICOM

#define NEP_MAGIC_DICOM   "DICM"

DICOM magic number: "DICM" prefix at byte offset 128

NEP_MAGIC_FITS

#define NEP_MAGIC_FITS   "SIMPLE"

FITS magic number: "SIMPLE" (first 6 bytes of a FITS file)

NEP_MAGIC_GEOTIFF_BIGTIFF

#define NEP_MAGIC_GEOTIFF_BIGTIFF   "II+"

GeoTIFF BigTIFF magic number: "II+"

NEP_MAGIC_GEOTIFF_STANDARD

#define NEP_MAGIC_GEOTIFF_STANDARD   "II*"

GeoTIFF standard TIFF magic number: "II*"

NEP_MAGIC_GRIB2

#define NEP_MAGIC_GRIB2   "GRIB"

GRIB2 magic number: "GRIB"

NEP_MAGIC_MMCIF

#define NEP_MAGIC_MMCIF   "data_"

PDBx/mmCIF magic number: "data_" token at the start of the file

NEP_MAGIC_PDB

#define NEP_MAGIC_PDB   "HEADER"

Legacy PDB magic number: "HEADER" record name at the start of the file

NEP_MAGIC_PDS4

#define NEP_MAGIC_PDS4   "<?xml"

PDS4 magic number: XML label files begin with "<?xml"