## sdfopen

`sdfopen filename <template #timesteps>`

Opens a NetCDF or HDF-SDS format file that conforms to the COARDS conventions. The arguments and options are as follows:

`filename`

The name of the COARDS-compliant NetCDF or HDF-SDS file.

`template`

This optional argument is used when you want to aggregate multiple data files and handle them as if they were one individual file. The individual data files must be identical in all dimensions except time. `template` has a similar structure to the substitution template in a GrADS data descriptor file. See Using Templates for details.

`#timesteps`

This argument must be included whenever `template` is invoked. The `#timesteps` is the sum of the timestep counts in all the files to be examined, not the count in any one file.

### Usage Notes

1. Any particular data file in the group described by the `template` is automatically accessed as the "time" or "t" settings in GrADS are altered.

2. Use `xdfopen` to open a non-COARDS-compliant self-describing file.

3. For additional information, see The Self-Describing Files (SDF) Interface.

### Examples

1. If you had daily U-Wind data in two files, `uwnd.1989.nc` and `uwnd.1990.nc`, you could access them both as one GrADS data set by entering:

   `sdfopen /data/uwnd.1989.nc uwnd.%y4.nc 730`