This function defines data fields to be stored in the grid. The dimensions are entered as a string consisting of geolocation dimensions separated by commas. The API will attempt to merge into a single object those fields that share dimensions and in case of multidimensional fields, numbertype. If the MERGE keyword is not set, the API will not attempt to merge it with other fields. Fields using the unlimited dimension will not be merged. Because merging breaks the one-to-one correspondence between HDF-EOS fields and HDF SDS arrays, it should not be set if the user wishes to access the HDF-EOS fields directly using HDF.

Note: Array ordering of variables used or returned by this routine changed in IDL 5.5. Programs written for versions of this routine prior to IDL 5.5 may need to be modified to work correctly with the current version.


In this example, we define a grid field, Temperature with dimensions XDim and YDim (as established by the EOS_GD_CREATE routine) containing 4-byte floating point numbers and a field, Spectra, with dimensions XDim, YDim, and Bands:

status = EOS_GD_DEFFIELD(gridID, "Temperature", &
   "YDim,XDim", 5, /MERGE)
status = EOS_GD_DEFFIELD(gridID, "Spectra", "Bands,YDim,XDim", 5)


Result = EOS_GD_DEFFIELD(gridID, fieldname, dimlist, numbertype [, /MERGE])

Return Value

Returns SUCCEED(0) if successful and FAIL(–1) otherwise.



Grid id (long) returned by EOS_GD_CREATE or EOS_GD_ATTACH.


Name of field (string) to be defined.


The list of data dimensions (string) defining the field.


The HDF data type (long) of the data stored in the field



If set, automerge will occur.

Version History