HDF_SD_START function opens or creates an HDF file and initializes the SD interface. The returned value of this function is the SD ID of the HDF file. If no keywords are present, the file is opened in read-only mode.
Note that every file opened with HDF_SD_START should eventually be closed with a call to HDF_SD_END.
Result = HDF_SD_START(
A scalar string containing the name of the file to be opened or created. HDF_SD_START can open the following file types: XDR-based NetCDF files, "old-style" DFSD files, or "new-style" SD files. New files are created as "new-style" SD files.
Set this keyword to open the SD interface in read-only mode. If no keywords are specified, this is the default behavior.
Set this keyword to open the SD interface in read and write mode.
Set this keyword to create a new SD file.
sd_id = HDF_SD_START('test.hdf', /CREATE)
For a more complicated example, see the documentation for HDF_SD_ATTRSET.