diff --git a/ncgen/main.c b/ncgen/main.c
index de24a166c..daec68a77 100644
--- a/ncgen/main.c
+++ b/ncgen/main.c
@@ -65,27 +65,36 @@ int main( int argc, char** argv );
 
 /* Define tables vs modes for legal -k values*/
 struct Kvalues legalkinds[NKVALUES] = {
-    {"1", 1},
-    {"classic", 1},
+    /* NetCDF-3 classic format (32-bit offsets) */
+    {"classic", NC_FORMAT_CLASSIC}, /* canonical format name */
+    {"nc3", NC_FORMAT_CLASSIC},	    /* short format name */
+    {"1", NC_FORMAT_CLASSIC},	/* deprecated, use "-3" or "-k nc3" instead */
+	
+    /* NetCDF-3 64-bit offset format */
+    {"64-bit offset", NC_FORMAT_64BIT}, /* canonical format name */
+    {"nc6", NC_FORMAT_64BIT},		/* short format name */
+    {"2", NC_FORMAT_64BIT},     /* deprecated, use "-6" or "-k nc6" instead */
+    {"64-bit-offset", NC_FORMAT_64BIT}, /* aliases */
+	
+    /* NetCDF-4 HDF5-based format */
+    {"netCDF-4", NC_FORMAT_NETCDF4}, /* canonical format name */
+    {"nc4", NC_FORMAT_NETCDF4},	     /* short format name */
+    {"3", NC_FORMAT_NETCDF4},   /* deprecated, use "-4" or "-k nc4" instead */
+    {"netCDF4", NC_FORMAT_NETCDF4},  /* aliases */
+    {"hdf5", NC_FORMAT_NETCDF4},
+    {"enhanced", NC_FORMAT_NETCDF4},
+    {"netcdf-4", NC_FORMAT_NETCDF4},
+    {"netcdf4", NC_FORMAT_NETCDF4},
 
-/* The 64-bit offset kind (2)  should only be used if actually needed */
-    {"2", 2},
-    {"64-bit-offset", 2},
-    {"64-bit offset", 2},
-
-    /* NetCDF-4 HDF5 format*/
-    {"3", 3},
-    {"hdf5", 3},
-    {"netCDF-4", 3},
-    {"netcdf-4", 3},
-    {"netcdf4", 3},
-    {"enhanced", 3},
-
-    /* NetCDF-4 HDF5 format, but using only nc3 data model */
-    {"4", 4},
-    {"hdf5-nc3", 4},
-    {"netCDF-4 classic model", 4},
-    {"enhanced-nc3", 4},
+    /* NetCDF-4 HDF5-based format, restricted to classic data model */
+    {"netCDF-4 classic model", NC_FORMAT_NETCDF4_CLASSIC}, /* canonical format name */
+    {"nc7", NC_FORMAT_NETCDF4_CLASSIC}, /* short format name */
+    {"4", NC_FORMAT_NETCDF4_CLASSIC}, /* deprecated, use "-7" or -k nc7" instead */
+    {"netCDF-4-classic", NC_FORMAT_NETCDF4_CLASSIC}, /* aliases */
+    {"netCDF-4_classic", NC_FORMAT_NETCDF4_CLASSIC},
+    {"netCDF4_classic", NC_FORMAT_NETCDF4_CLASSIC},
+    {"hdf5-nc3", NC_FORMAT_NETCDF4_CLASSIC},
+    {"enhanced-nc3", NC_FORMAT_NETCDF4_CLASSIC},
 
     /* null terminate*/
     {NULL,0}
@@ -206,7 +215,7 @@ main(
     (void) par_io_init(32, 32);
 #endif
 
-    while ((c = getopt(argc, argv, "hbcfk:l:no:v:xdM:D:B:P")) != EOF)
+    while ((c = getopt(argc, argv, "hbcfk:3467l:no:v:xdM:D:B:P")) != EOF)
       switch(c) {
 	case 'd':
 	  debug = 1;
@@ -283,18 +292,18 @@ main(
 	  break;
         case 'v': /* a deprecated alias for "kind" option */
 	    /*FALLTHRU*/
-        case 'k': /* for specifying variant of netCDF format to be generated
-                     Possible values are:
-                     1 (=> classic 32 bit)
-                     2 (=> classic 64 bit)
-                     3 (=> enhanced)
-                     4 (=> classic, but stored in an enhanced file format)
-                     Also provide string versions of above
-                     "classic"
-                     "64-bit-offset"
-                     "64-bit offset"
-		     "enhanced" | "hdf5" | "netCDF-4"
-                     "enhanced-nc3" | "hdf5-nc3" | "netCDF-4 classic model"
+	case 'k': /* for specifying variant of netCDF format to be generated
+		     Possible values are:
+		     Format names:
+		       "classic" or "nc3"
+		       "64-bit offset" or "nc6"
+		       "netCDF-4" or "nc4"
+		       "netCDF-4 classic model" or "nc7"
+		     Format version numbers (deprecated):
+		       1 (=> classic)
+		       2 (=> 64-bit offset)
+		       3 (=> netCDF-4)
+		       4 (=> netCDF-4 classic model)
 		   */
 	    {
 		struct Kvalues* kvalue;
@@ -317,6 +326,18 @@ main(
 		}
 	    }
 	  break;
+	case '3':		/* output format is classic (netCDF-3) */
+	    k_flag = NC_FORMAT_CLASSIC;
+	    break;
+	case '6':		/* output format is 64-bit-offset (netCDF-3 version 2) */
+	    k_flag = NC_FORMAT_64BIT;
+	    break;
+	case '4':		/* output format is netCDF-4 (variant of HDF5) */
+	    k_flag = NC_FORMAT_NETCDF4;
+	    break;
+	case '7':		/* output format is netCDF-4 (restricted to classic model)*/
+	    k_flag = NC_FORMAT_NETCDF4_CLASSIC;
+	    break;
 	case 'M': /* Determine the name for the main function */
 	    mainname = nulldup(optarg);
 	    break;
diff --git a/ncgen/ncgen.1 b/ncgen/ncgen.1
index 8cdc49440..2e53b60d5 100644
--- a/ncgen/ncgen.1
+++ b/ncgen/ncgen.1
@@ -9,7 +9,8 @@ ncgen
 \%[-b]
 \%[-c]
 \%[-f]
-\%[-k \fIfile format\fP]
+\%[-k \fIformat_name\fP]
+\%[-\fIformat_code\fP]
 \%[-l \fIoutput language\fP]
 \%[-n]
 \%[-o \fInetcdf_filename\fP]
@@ -67,22 +68,41 @@ If this option is specified it implies
 This option is necessary because netCDF files
 cannot be written directly to standard output, since standard output is not
 seekable.
-.IP "\fB-k \fRfile_format\fP"
+.IP "\fB-k \fIformat_name\fP"
+.IP "\fB-\fIformat_code\fP"
 The -k flag specifies the format of the file to be created and, by inference,
 the data model accepted by ncgen (i.e. netcdf-3 (classic) versus
-netcdf-4).
-The possible arguments are as follows.
+netcdf-4). As a shortcut, a numeric \fIformat_code\fP may be specified instead.
+The possible \fIformat_name\fP values for the -k option are:
 .RS
 .RS
-.IP "'1', 'classic' => netcdf classic file format, netcdf-3 type model."
-.IP "'2', '64-bit-offset', '64-bit offset' => netcdf 64 bit classic file format, netcdf-3 type model."
-.IP "'3', 'hdf5', 'netCDF-4', 'enhanced' => netcdf-4 file format, netcdf-4 type model."
-.IP "'4', 'hdf5-nc3', 'netCDF-4 classic model', 'enhanced-nc3' => netcdf-4 file format, netcdf-3 type model."
+.IP "'classic' or 'nc3' => netCDF classic format"
+.IP "'64-bit-offset' or 'nc6' => netCDF 64-bit format"
+.IP "'netCDF-4' 0r 'nc4' => netCDF-4 format (enhanced data model)"
+.IP "'netCDF-4 classic model' or 'nc7' => netCDF-4 classic model format"
 .RE
 .RE
-Note that -v is accepted to mean the same thing as
--k for backward compatibility, but -k is preferred, to match
-the corresponding ncdump option. 
+Accepted \fIformat_number\fP arguments, just shortcuts for format_names, are:
+.RS
+.RS
+.IP "3 => netcdf classic format"
+.IP "6 => netCDF 64-bit format"
+.IP "4 => netCDF-4 format (enhanced data model)"
+.IP "7 => netCDF-4 classic model format"
+.RE
+.RE
+The numeric code "7" is used because "7=3+4", a mnemonic for the format
+that uses the netCDF-3 data model for compatibility with the netCDF-4
+storage format for performance. Credit is due to NCO for use of these
+numeric codes instead of the old and confusing format numbers.
+.LP
+Note: The old version format numbers '1', '2', '3', '4', equivalent
+to the format names 'nc3', 'nc6', 'nc4', or 'nc7' respectively, are
+also still accepted but deprecated, due to easy confusion between
+format numbers and format names. Various old format name aliases are
+also accepted but deprecated, e.g. 'hdf5', 'enhanced-nc3', etc.
+Also, note that -v is accepted to mean the same thing as
+-k for backward compatibility.
 .IP "\fB-x\fP"
 Don't initialize data with fill values.  This can speed up creation of
 large netCDF files greatly, but later attempts to read unwritten data
diff --git a/ncgen/ncgen.h b/ncgen/ncgen.h
index dc508a6fb..0b36e7f3e 100644
--- a/ncgen/ncgen.h
+++ b/ncgen/ncgen.h
@@ -103,7 +103,7 @@ char* name;
 int k_flag;
 };
 
-#define NKVALUES 16
+#define NKVALUES 24
 extern struct Kvalues legalkinds[NKVALUES];
 
 /* Note: some non-var specials (i.e. _Format) are not included in this struct*/