diff --git a/ncgen/ncgen.y b/ncgen/ncgen.y
index d959d4d78..1a0293d5b 100644
--- a/ncgen/ncgen.y
+++ b/ncgen/ncgen.y
@@ -185,7 +185,7 @@ NCConstant       constant;
         _ENDIANNESS
         _NOFILL
         _FLETCHER32
-	DATASETID	
+	DATASETID
 
 %type <sym> ident typename primtype dimd varspec
 	    attrdecl enumid path dimref fielddim fieldspec
@@ -233,7 +233,7 @@ namedgroup: GROUP ident '{'
             {
 		Symbol* id = $2;
                 markcdf4("Group specification");
-		if(creategroup(id) == NULL) 
+		if(creategroup(id) == NULL)
                     yyerror("duplicate group declaration within parent group for %s",
                                 id->name);
             }
@@ -243,7 +243,7 @@ namedgroup: GROUP ident '{'
             '}'
 	    attrdecllist
 	    ;
-      
+
 typesection:    /* empty */
                 | TYPES {}
 		| TYPES typedecls
@@ -299,7 +299,7 @@ enumdecl: primtype ENUM typename
                    listpush($3->subnodes,(void*)eid);
                    eid->container = $3;
 		   eid->typ.basetype = $3->typ.basetype;
-                }               
+                }
                 listsetlength(stack,stackbase);/* remove stack nodes*/
               }
           ;
@@ -318,7 +318,7 @@ enumidlist:   enumid
 		      if(strcmp($3->name,elem->name)==0)
   	                yyerror("duplicate enum declaration for %s",
         	                 elem->name);
-		    }    	    
+		    }
 		    listpush(stack,(void*)$3);
 		}
 	    ;
@@ -385,7 +385,7 @@ compounddecl: COMPOUND typename '{' fields '}'
 	        Symbol* fsym = (Symbol*)listget(stack,i);
 		fsym->container = $2;
  	        listpush($2->subnodes,(void*)fsym);
-	    }    	    
+	    }
 	    listsetlength(stack,stackbase);/* remove stack nodes*/
           }
             ;
@@ -480,7 +480,7 @@ fprintf(stderr,"dimension: %s = UNLIMITED\n",$1->name);
                 ;
 
 dimd:           ident
-                   { 
+                   {
                      $1->objectclass=NC_DIM;
                      if(dupobjectcheck(NC_DIM,$1))
                         yyerror( "Duplicate dimension declaration for %s",
@@ -672,7 +672,7 @@ varref:
 	  ;
 
 typeref:
-	type_var_ref	  
+	type_var_ref
 	    {Symbol* tsym = $1;
 		if(tsym->objectclass != NC_TYPE) {
 		    derror("Undefined or forward referenced type: %s",tsym->name);
@@ -682,8 +682,8 @@ typeref:
 	    }
 	;
 
-type_var_ref: 
-	path 
+type_var_ref:
+	path
 	    {Symbol* tvsym = $1; Symbol* sym;
 		/* disambiguate*/
 		tvsym->objectclass = NC_VAR;
@@ -956,7 +956,7 @@ install(const char *sname)
 {
     Symbol* sp;
     sp = (Symbol*) emalloc (sizeof (struct Symbol));
-    memset((void*)sp,0,sizeof(struct Symbol));    
+    memset((void*)sp,0,sizeof(struct Symbol));
     sp->name = nulldup(sname);
     sp->next = symlist;
     sp->lineno = lineno;
@@ -1028,7 +1028,7 @@ makeconstdata(nc_type nctype)
 	    len = bbLength(lextext);
 	    con.value.stringv.len = len;
 	    con.value.stringv.stringv = bbDup(lextext);
-	    bbClear(lextext);	    
+	    bbClear(lextext);
 	    }
 	    break;
 
@@ -1061,7 +1061,7 @@ makeconstdata(nc_type nctype)
 	default:
 	    yyerror("Data constant: unexpected NC type: %s",
 		    nctypename(nctype));
-	    con.value.stringv.stringv = NULL;    
+	    con.value.stringv.stringv = NULL;
 	    con.value.stringv.len = 0;
     }
     return con;
@@ -1233,7 +1233,7 @@ makespecial(int tag, Symbol* vsym, Symbol* tsym, void* data, int isconst)
 	break;
     default: PANIC1("unexpected special tag: %d",tag);
     }
-    
+
     if(tag == _FORMAT_FLAG) {
 	/* Watch out: this is a global attribute */
 	struct Kvalues* kvalue;
@@ -1241,11 +1241,13 @@ makespecial(int tag, Symbol* vsym, Symbol* tsym, void* data, int isconst)
 
 	/* Use the table in main.c */
         for(kvalue = legalkinds; kvalue->name; kvalue++) {
-	    if(strcmp(sdata, kvalue->name) == 0) {
-		/*Main.*/format_flag = kvalue->k_flag;
-		found = 1;
-	        break;
-	    }
+          if(sdata) {
+            if(strcmp(sdata, kvalue->name) == 0) {
+              /*Main.*/format_flag = kvalue->k_flag;
+              found = 1;
+              break;
+            }
+          }
 	}
 	if(!found)
 	    derror("_Format: illegal value: %s",sdata);
@@ -1278,15 +1280,17 @@ makespecial(int tag, Symbol* vsym, Symbol* tsym, void* data, int isconst)
         } else switch (tag) {
 	    // These will be output as attributes later
             case _STORAGE_FLAG:
-                if(strcmp(sdata,"contiguous") == 0)
-                    special->_Storage = NC_CONTIGUOUS;
-                else if(strcmp(sdata,"chunked") == 0)
-                    special->_Storage = NC_CHUNKED;
-                else
-                    derror("_Storage: illegal value: %s",sdata);
-                special->flags |= _STORAGE_FLAG;
-                break;
-            case _FLETCHER32_FLAG:
+              if(!sdata)
+                derror("_Storage: illegal NULL value");
+              else if(strcmp(sdata,"contiguous") == 0)
+                special->_Storage = NC_CONTIGUOUS;
+              else if(strcmp(sdata,"chunked") == 0)
+                special->_Storage = NC_CHUNKED;
+              else
+                derror("_Storage: illegal value: %s",sdata);
+              special->flags |= _STORAGE_FLAG;
+              break;
+          case _FLETCHER32_FLAG:
                 special->_Fletcher32 = tf;
                 special->flags |= _FLETCHER32_FLAG;
                 break;
@@ -1299,15 +1303,17 @@ makespecial(int tag, Symbol* vsym, Symbol* tsym, void* data, int isconst)
                 special->flags |= _SHUFFLE_FLAG;
                 break;
             case _ENDIAN_FLAG:
-                if(strcmp(sdata,"little") == 0)
-                    special->_Endianness = 1;
-                else if(strcmp(sdata,"big") == 0)
-                    special->_Endianness = 2;
-                else
-                    derror("_Endianness: illegal value: %s",sdata);
-                special->flags |= _ENDIAN_FLAG;
-                break;
-            case _NOFILL_FLAG:
+              if(!sdata)
+                derror("_Endianness: illegal NULL value");
+              else if(strcmp(sdata,"little") == 0)
+                special->_Endianness = 1;
+              else if(strcmp(sdata,"big") == 0)
+                special->_Endianness = 2;
+              else
+                derror("_Endianness: illegal value: %s",sdata);
+              special->flags |= _ENDIAN_FLAG;
+              break;
+          case _NOFILL_FLAG:
                 special->_Fill = (1 - tf); /* negate */
                 special->flags |= _NOFILL_FLAG;
                 break;
@@ -1374,8 +1380,8 @@ containsfills(Datalist* list)
         NCConstant* con = list->data;
         for(i=0;i<list->length;i++,con++) {
 	    if(con->nctype == NC_COMPOUND) {
-	        if(containsfills(con->value.compoundv)) return 1;	
-	    } else if(con->nctype == NC_FILLVALUE) return 1;	
+	        if(containsfills(con->value.compoundv)) return 1;
+	    } else if(con->nctype == NC_FILLVALUE) return 1;
 	}
     }
     return 0;
@@ -1443,7 +1449,7 @@ evaluate(Symbol* fcn, Datalist* arglist)
 	    }
 	    break;
 	case 0:
-	default: 
+	default:
 	    derror("Expected function signature: time([string,]string)");
 	    goto done;
 	}
@@ -1458,9 +1464,9 @@ evaluate(Symbol* fcn, Datalist* arglist)
 	    cdCalenType timetype = cdStandard;
 	    cdChar2Comp(timetype,timevalue,&comptime);
 	    /* convert comptime to cdTime */
-	    cdtime.year = comptime.year;	    
+	    cdtime.year = comptime.year;
 	    cdtime.month = comptime.month;
-	    cdtime.day = comptime.day;    
+	    cdtime.day = comptime.day;
 	    cdtime.hour = comptime.hour;
 	    cdtime.baseYear = 1970;
 	    cdtime.timeType = CdChron;
@@ -1478,4 +1484,3 @@ evaluate(Symbol* fcn, Datalist* arglist)
 done:
     return result;
 }
-
diff --git a/ncgen/ncgentab.c b/ncgen/ncgentab.c
index 03b6b3443..fed41d056 100644
--- a/ncgen/ncgentab.c
+++ b/ncgen/ncgentab.c
@@ -1598,7 +1598,7 @@ yyreduce:
     {
 		Symbol* id = (yyvsp[-1].sym);
                 markcdf4("Group specification");
-		if(creategroup(id) == NULL) 
+		if(creategroup(id) == NULL)
                     yyerror("duplicate group declaration within parent group for %s",
                                 id->name);
             }
@@ -1672,7 +1672,7 @@ yyreduce:
                    listpush((yyvsp[-3].sym)->subnodes,(void*)eid);
                    eid->container = (yyvsp[-3].sym);
 		   eid->typ.basetype = (yyvsp[-3].sym)->typ.basetype;
-                }               
+                }
                 listsetlength(stack,stackbase);/* remove stack nodes*/
               }
 #line 1679 "ncgentab.c" /* yacc.c:1646  */
@@ -1697,7 +1697,7 @@ yyreduce:
 		      if(strcmp((yyvsp[0].sym)->name,elem->name)==0)
   	                yyerror("duplicate enum declaration for %s",
         	                 elem->name);
-		    }    	    
+		    }
 		    listpush(stack,(void*)(yyvsp[0].sym));
 		}
 #line 1704 "ncgentab.c" /* yacc.c:1646  */
@@ -1772,7 +1772,7 @@ yyreduce:
 	        Symbol* fsym = (Symbol*)listget(stack,i);
 		fsym->container = (yyvsp[-3].sym);
  	        listpush((yyvsp[-3].sym)->subnodes,(void*)fsym);
-	    }    	    
+	    }
 	    listsetlength(stack,stackbase);/* remove stack nodes*/
           }
 #line 1779 "ncgentab.c" /* yacc.c:1646  */
@@ -1953,7 +1953,7 @@ fprintf(stderr,"dimension: %s = UNLIMITED\n",(yyvsp[-2].sym)->name);
 
   case 59:
 #line 483 "ncgen.y" /* yacc.c:1646  */
-    { 
+    {
                      (yyvsp[0].sym)->objectclass=NC_DIM;
                      if(dupobjectcheck(NC_DIM,(yyvsp[0].sym)))
                         yyerror( "Duplicate dimension declaration for %s",
@@ -2934,7 +2934,7 @@ install(const char *sname)
 {
     Symbol* sp;
     sp = (Symbol*) emalloc (sizeof (struct Symbol));
-    memset((void*)sp,0,sizeof(struct Symbol));    
+    memset((void*)sp,0,sizeof(struct Symbol));
     sp->name = nulldup(sname);
     sp->next = symlist;
     sp->lineno = lineno;
@@ -3006,7 +3006,7 @@ makeconstdata(nc_type nctype)
 	    len = bbLength(lextext);
 	    con.value.stringv.len = len;
 	    con.value.stringv.stringv = bbDup(lextext);
-	    bbClear(lextext);	    
+	    bbClear(lextext);
 	    }
 	    break;
 
@@ -3039,7 +3039,7 @@ makeconstdata(nc_type nctype)
 	default:
 	    yyerror("Data constant: unexpected NC type: %s",
 		    nctypename(nctype));
-	    con.value.stringv.stringv = NULL;    
+	    con.value.stringv.stringv = NULL;
 	    con.value.stringv.len = 0;
     }
     return con;
@@ -3211,7 +3211,7 @@ makespecial(int tag, Symbol* vsym, Symbol* tsym, void* data, int isconst)
 	break;
     default: PANIC1("unexpected special tag: %d",tag);
     }
-    
+
     if(tag == _FORMAT_FLAG) {
 	/* Watch out: this is a global attribute */
 	struct Kvalues* kvalue;
@@ -3219,11 +3219,13 @@ makespecial(int tag, Symbol* vsym, Symbol* tsym, void* data, int isconst)
 
 	/* Use the table in main.c */
         for(kvalue = legalkinds; kvalue->name; kvalue++) {
-	    if(strcmp(sdata, kvalue->name) == 0) {
-		/*Main.*/format_flag = kvalue->k_flag;
-		found = 1;
-	        break;
-	    }
+          if(sdata) {
+            if(strcmp(sdata, kvalue->name) == 0) {
+              /*Main.*/format_flag = kvalue->k_flag;
+              found = 1;
+              break;
+            }
+          }
 	}
 	if(!found)
 	    derror("_Format: illegal value: %s",sdata);
@@ -3254,16 +3256,18 @@ makespecial(int tag, Symbol* vsym, Symbol* tsym, void* data, int isconst)
             }
             attr = makeattribute(install("_FillValue"),vsym,tsym,list,ATTRVAR);
         } else switch (tag) {
-	    // These will be output as attributes later
-            case _STORAGE_FLAG:
-                if(strcmp(sdata,"contiguous") == 0)
-                    special->_Storage = NC_CONTIGUOUS;
-                else if(strcmp(sdata,"chunked") == 0)
-                    special->_Storage = NC_CHUNKED;
-                else
-                    derror("_Storage: illegal value: %s",sdata);
-                special->flags |= _STORAGE_FLAG;
-                break;
+            // These will be output as attributes later
+          case _STORAGE_FLAG:
+            if(!sdata)
+              derror("_Storage: illegal NULL value");
+            else if(strcmp(sdata,"contiguous") == 0)
+              special->_Storage = NC_CONTIGUOUS;
+            else if(strcmp(sdata,"chunked") == 0)
+              special->_Storage = NC_CHUNKED;
+            else
+              derror("_Storage: illegal value: %s",sdata);
+            special->flags |= _STORAGE_FLAG;
+            break;
             case _FLETCHER32_FLAG:
                 special->_Fletcher32 = tf;
                 special->flags |= _FLETCHER32_FLAG;
@@ -3277,15 +3281,17 @@ makespecial(int tag, Symbol* vsym, Symbol* tsym, void* data, int isconst)
                 special->flags |= _SHUFFLE_FLAG;
                 break;
             case _ENDIAN_FLAG:
-                if(strcmp(sdata,"little") == 0)
-                    special->_Endianness = 1;
-                else if(strcmp(sdata,"big") == 0)
-                    special->_Endianness = 2;
-                else
-                    derror("_Endianness: illegal value: %s",sdata);
-                special->flags |= _ENDIAN_FLAG;
-                break;
-            case _NOFILL_FLAG:
+              if(!sdata)
+                derror("_Endianness: NULL value.");
+              else if(strcmp(sdata,"little") == 0)
+                special->_Endianness = 1;
+              else if(strcmp(sdata,"big") == 0)
+                special->_Endianness = 2;
+              else
+                derror("_Endianness: illegal value: %s",sdata);
+              special->flags |= _ENDIAN_FLAG;
+              break;
+          case _NOFILL_FLAG:
                 special->_Fill = (1 - tf); /* negate */
                 special->flags |= _NOFILL_FLAG;
                 break;
@@ -3352,8 +3358,8 @@ containsfills(Datalist* list)
         NCConstant* con = list->data;
         for(i=0;i<list->length;i++,con++) {
 	    if(con->nctype == NC_COMPOUND) {
-	        if(containsfills(con->value.compoundv)) return 1;	
-	    } else if(con->nctype == NC_FILLVALUE) return 1;	
+	        if(containsfills(con->value.compoundv)) return 1;
+	    } else if(con->nctype == NC_FILLVALUE) return 1;
 	}
     }
     return 0;
@@ -3421,7 +3427,7 @@ evaluate(Symbol* fcn, Datalist* arglist)
 	    }
 	    break;
 	case 0:
-	default: 
+	default:
 	    derror("Expected function signature: time([string,]string)");
 	    goto done;
 	}
@@ -3436,9 +3442,9 @@ evaluate(Symbol* fcn, Datalist* arglist)
 	    cdCalenType timetype = cdStandard;
 	    cdChar2Comp(timetype,timevalue,&comptime);
 	    /* convert comptime to cdTime */
-	    cdtime.year = comptime.year;	    
+	    cdtime.year = comptime.year;
 	    cdtime.month = comptime.month;
-	    cdtime.day = comptime.day;    
+	    cdtime.day = comptime.day;
 	    cdtime.hour = comptime.hour;
 	    cdtime.baseYear = 1970;
 	    cdtime.timeType = CdChron;
@@ -3456,4 +3462,3 @@ evaluate(Symbol* fcn, Datalist* arglist)
 done:
     return result;
 }
-