added more documentation to nc_def_var_filter()

libdispatch/dvar.c

@@ -667,18 +667,26 @@ nc_def_var_endian(int ncid, int varid, int endian)
 }
 
 /**
-   Define a new variable filter.
-
-   @param ncid File and group ID.
-   @param varid Variable ID.
-   @param id
-   @param nparams Number of filter parameters.
-   @param parms Filter parameters.
-
-   @return ::NC_NOERR No error.
-   @return ::NC_EBADID Bad ID.
-   @author Dennis Heimbigner
-*/
+ * Define a new variable filter.
+ *
+ * HDF5 filters are plug-in libraries which can modify data when it is
+ * being read or written.
+ *
+ * @note Variables must be chunked to use filters. Calling
+ * nc_def_var_filter() on a variable causes its storage to be changed
+ * to chunked; default chunksizes are selected.
+ *
+ * @param ncid File and group ID.
+ * @param varid Variable ID.
+ * @param id ID of the HDF5 filter.
+ * @param nparams Number of filter parameters.
+ * @param parms Filter parameters.
+ *
+ * @return ::NC_NOERR No error.
+ * @return ::NC_EBADID Bad ID.
+ * @return ::NC_EFILTER Filter error.
+ * @author Dennis Heimbigner
+ */
 int
 nc_def_var_filter(int ncid, int varid, unsigned int id,
                   size_t nparams, const unsigned int* parms)