Index: netcdfdataset.h
===================================================================
--- netcdfdataset.h	(revision 23000)
+++ netcdfdataset.h	(working copy)
@@ -92,7 +92,15 @@
 
 #define GDALNBDIM  2
 
+/* netcdf file types, as in libcdi/cdo */
+#define NCDF_FILETYPE_NONE            0
+#define NCDF_FILETYPE_NC              1   /* File type netCDF                     */
+#define NCDF_FILETYPE_NC2             2   /* File type netCDF version 2 (64-bit)  */
+#define NCDF_FILETYPE_NC4             3   /* File type netCDF version 4           */
+#define NCDF_FILETYPE_NC4C            4   /* File type netCDF version 4 (classic) */
+#define NCDF_FILETYPE_UNKNOWN         10
 
+
 typedef struct {
     const char *netCDFSRS;
     const char *SRS; }
@@ -176,10 +184,12 @@
     size_t        xdim, ydim;
     int           nDimXid, nDimYid;
     bool          bBottomUp;
+    int           nFiletype;
 
-		netCDFDataset( );
-		~netCDFDataset( );
+    netCDFDataset( );
+    ~netCDFDataset( );
     
+    static int Identify( GDALOpenInfo * );
     static GDALDataset *Open( GDALOpenInfo * );
 
     CPLErr      SafeStrcat(char**, char*, size_t*);
Index: netcdfdataset.cpp
===================================================================
--- netcdfdataset.cpp	(revision 23000)
+++ netcdfdataset.cpp	(working copy)
@@ -1919,6 +1919,33 @@
 }
     
 /************************************************************************/
+/*                              Identify()                              */
+/************************************************************************/
+
+int netCDFDataset::Identify( GDALOpenInfo * poOpenInfo )
+
+{
+/* -------------------------------------------------------------------- */
+/*      Does this appear to be a netcdf file?                           */
+/*      Note: proper care should be done at configure to detect which   */
+/*        netcdf versions are supported (nc, nc2, nc4), as does CDO     */
+/* -------------------------------------------------------------------- */
+    if ( poOpenInfo->nHeaderBytes < 4 )
+        return NCDF_FILETYPE_NONE;
+    if ( EQUALN((char*)poOpenInfo->pabyHeader,"CDF\001",4) )
+        return NCDF_FILETYPE_NC;
+    else if ( EQUALN((char*)poOpenInfo->pabyHeader,"CDF\002",4) )
+        return NCDF_FILETYPE_NC2;
+    else if ( EQUALN((char*)poOpenInfo->pabyHeader+1,"HDF",3) ) {
+        /* requires netcdf v4, should also test for netCDF-4 support compiled in */
+        if ( nc_inq_libvers()[0]=='4' )
+           return NCDF_FILETYPE_NC4;
+    }
+
+    return NCDF_FILETYPE_NONE;
+} 
+
+/************************************************************************/
 /*                                Open()                                */
 /************************************************************************/
 
@@ -1939,14 +1966,16 @@
     int          ndims, nvars, ngatts, unlimdimid;
     int          nCount=0;
     int          nVarID=-1;
+    int          nTmpFiletype=NCDF_FILETYPE_NONE;
 
 /* -------------------------------------------------------------------- */
 /*      Does this appear to be a netcdf file?                           */
 /* -------------------------------------------------------------------- */
-    if( !EQUALN(poOpenInfo->pszFilename,"NETCDF:",7)
-        && ( poOpenInfo->nHeaderBytes < 5 
-             || !EQUALN((const char *) (poOpenInfo->pabyHeader),"CDF\001",5)))
-        return NULL;
+   if( ! EQUALN(poOpenInfo->pszFilename,"NETCDF:",7) ) {
+      nTmpFiletype = Identify( poOpenInfo );
+      if ( nTmpFiletype == NCDF_FILETYPE_NONE ) 
+       return NULL;
+    }
 
 /* -------------------------------------------------------------------- */
 /*       Check if filename start with NETCDF: tag                       */
@@ -1990,11 +2019,14 @@
                       "Failed to parse NETCDF: prefix string into expected three fields." );
             return NULL;
         }
+       /* should try to identify filetype */ 
+       poDS->nFiletype = NCDF_FILETYPE_UNKNOWN;
     }
     else 
     {
         poDS->osFilename = poOpenInfo->pszFilename;
         poDS->bTreatAsSubdataset = FALSE;
+        poDS->nFiletype = nTmpFiletype;
     }
 
 /* -------------------------------------------------------------------- */