diff --git a/qse/include/qse/awk/awk.h b/qse/include/qse/awk/awk.h
index 4417187b..2f178228 100644
--- a/qse/include/qse/awk/awk.h
+++ b/qse/include/qse/awk/awk.h
@@ -2349,7 +2349,7 @@ QSE_EXPORT int qse_awk_rtx_setrec (
 );
 
 /**
- * The qse_awk_rtx_isnilval(0 function determines if a value
+ * The qse_awk_rtx_isnilval() function determines if a value
  * is a nil value.
  */
 QSE_EXPORT int qse_awk_rtx_isnilval (
diff --git a/qse/lib/awk/fnc.c b/qse/lib/awk/fnc.c
index 5c402ecc..16217e2e 100644
--- a/qse/lib/awk/fnc.c
+++ b/qse/lib/awk/fnc.c
@@ -30,6 +30,7 @@ static int fnc_close (qse_awk_rtx_t* rtx, const qse_awk_fnc_info_t* fi);
 static int fnc_fflush (qse_awk_rtx_t* rtx, const qse_awk_fnc_info_t* fi);
 static int fnc_int (qse_awk_rtx_t* rtx, const qse_awk_fnc_info_t* fi);
 static int fnc_typename (qse_awk_rtx_t* rtx, const qse_awk_fnc_info_t* fi);
+static int fnc_isnil (qse_awk_rtx_t* rtx, const qse_awk_fnc_info_t* fi);
 static int fnc_asort (qse_awk_rtx_t* rtx, const qse_awk_fnc_info_t* fi);
 
 #define A_MAX QSE_TYPE_MAX(int)
@@ -59,6 +60,7 @@ static qse_awk_fnc_t sysfnctab[] =
 	/* type info/conversion */
 	{ {QSE_T("int"),      3}, 0, { {1,     1, QSE_NULL},       fnc_int,              0 }, QSE_NULL},
 	{ {QSE_T("typename"), 8}, 0, { {1,     1, QSE_NULL},       fnc_typename,         0 }, QSE_NULL},
+	{ {QSE_T("isnil"),    5}, 0, { {1,     1, QSE_NULL},       fnc_isnil,         0 }, QSE_NULL},
 
 	/* array sort */
 	{ {QSE_T("asort"),    5}, 0, { {1,     3, QSE_NULL},       fnc_asort,            0 }, QSE_NULL},
@@ -1497,6 +1499,20 @@ static int fnc_typename (qse_awk_rtx_t* rtx, const qse_awk_fnc_info_t* fi)
 	return 0;
 }
 
+static int fnc_isnil (qse_awk_rtx_t* rtx, const qse_awk_fnc_info_t* fi)
+{
+	qse_awk_val_t* a0;
+	qse_awk_val_t* r;
+
+	a0 = qse_awk_rtx_getarg(rtx, 0);
+
+	r = qse_awk_rtx_makeintval(rtx, QSE_AWK_RTX_GETVALTYPE(rtx, a0) == QSE_AWK_VAL_NIL);
+	if (r == QSE_NULL) return -1;
+
+	qse_awk_rtx_setretval (rtx, r);
+	return 0;
+}
+
 static int fnc_asort (qse_awk_rtx_t* rtx, const qse_awk_fnc_info_t* fi)
 {
 	qse_size_t nargs;
diff --git a/qse/lib/awk/parse.c b/qse/lib/awk/parse.c
index 72fd8a60..e55130dd 100644
--- a/qse/lib/awk/parse.c
+++ b/qse/lib/awk/parse.c
@@ -78,7 +78,6 @@ enum tok_t
 	TOK_MA,   /* ~ - match */
 	TOK_NM,   /* !~ -  not match */
 	TOK_LNOT, /* ! - logical negation */
-	TOK_BQUOTE,  /* ` - is-defined */
 	TOK_PLUS,
 	TOK_PLUSPLUS,
 	TOK_MINUS,
@@ -3909,7 +3908,6 @@ static qse_awk_nde_t* parse_concat (qse_awk_t* awk, const qse_awk_loc_t* xloc)
 			   /* unary operators */
 			   MATCH(awk,TOK_PLUS) || MATCH(awk,TOK_MINUS) ||
 			   MATCH(awk,TOK_LNOT) || MATCH(awk,TOK_BNOT) || 
-			   MATCH(awk,TOK_BQUOTE) ||
 			   /* increment operators */
 			   MATCH(awk,TOK_PLUSPLUS) || MATCH(awk,TOK_MINUSMINUS) ||
 			   ((awk->opt.trait & QSE_AWK_TOLERANT) && 
@@ -3979,8 +3977,7 @@ static qse_awk_nde_t* parse_unary (qse_awk_t* awk, const qse_awk_loc_t* xloc)
 	opcode = (MATCH(awk,TOK_PLUS))?  QSE_AWK_UNROP_PLUS:
 	         (MATCH(awk,TOK_MINUS))? QSE_AWK_UNROP_MINUS:
 	         (MATCH(awk,TOK_LNOT))?  QSE_AWK_UNROP_LNOT:
-	         (MATCH(awk,TOK_BNOT))?  QSE_AWK_UNROP_BNOT:
-	         (MATCH(awk,TOK_BQUOTE))? QSE_AWK_UNROP_DEF: -1;
+	         (MATCH(awk,TOK_BNOT))?  QSE_AWK_UNROP_BNOT: -1;
 
 	/*if (opcode <= -1) return parse_increment (awk);*/
 	if (opcode <= -1) return parse_exponent (awk, xloc);
@@ -4127,8 +4124,7 @@ static qse_awk_nde_t* parse_unary_exp (qse_awk_t* awk, const qse_awk_loc_t* xloc
 	opcode = (MATCH(awk,TOK_PLUS))?  QSE_AWK_UNROP_PLUS:
 	         (MATCH(awk,TOK_MINUS))? QSE_AWK_UNROP_MINUS:
 	         (MATCH(awk,TOK_LNOT))?  QSE_AWK_UNROP_LNOT:
-	         (MATCH(awk,TOK_BNOT))?  QSE_AWK_UNROP_BNOT: 
-	         (MATCH(awk,TOK_BQUOTE))? QSE_AWK_UNROP_DEF: -1;
+	         (MATCH(awk,TOK_BNOT))?  QSE_AWK_UNROP_BNOT: -1;
 
 	if (opcode <= -1) return parse_increment (awk, xloc);
 
@@ -6127,7 +6123,6 @@ static int get_symbols (qse_awk_t* awk, qse_cint_t c, qse_awk_tok_t* tok)
 		{ QSE_T("::"),  2, TOK_DBLCOLON,     0 },
 		{ QSE_T(":"),   1, TOK_COLON,        0 },
 		{ QSE_T("?"),   1, TOK_QUEST,        0 },
-		{ QSE_T("`"),   1, TOK_BQUOTE,       0 },
 		{ QSE_NULL,     0, 0,                0 }
 	};
 
diff --git a/qse/lib/awk/run.c b/qse/lib/awk/run.c
index 55bcdf1c..25697d74 100644
--- a/qse/lib/awk/run.c
+++ b/qse/lib/awk/run.c
@@ -5266,8 +5266,7 @@ static qse_awk_val_t* eval_unary (qse_awk_rtx_t* run, qse_awk_nde_t* nde)
 		exp->opcode == QSE_AWK_UNROP_PLUS ||
 		exp->opcode == QSE_AWK_UNROP_MINUS ||
 		exp->opcode == QSE_AWK_UNROP_LNOT ||
-		exp->opcode == QSE_AWK_UNROP_BNOT ||
-		exp->opcode == QSE_AWK_UNROP_DEF);
+		exp->opcode == QSE_AWK_UNROP_BNOT);
 
 	QSE_ASSERT (exp->left->next == QSE_NULL);
 	left = eval_expression (run, exp->left);
@@ -5317,12 +5316,6 @@ static qse_awk_val_t* eval_unary (qse_awk_rtx_t* run, qse_awk_nde_t* nde)
 			res = (n == 0)? qse_awk_rtx_makeintval (run, l):
 			                qse_awk_rtx_makefltval (run, r);
 			break;
-
-		case QSE_AWK_UNROP_DEF:
-			/* is defined? */
-			res = qse_awk_rtx_makeintval (
-				run, ((QSE_AWK_RTX_GETVALTYPE (rtx, left) == QSE_AWK_VAL_NIL)? 0: 1));
-			break;
 	}
 
 exit_func:
diff --git a/qse/lib/awk/run.h b/qse/lib/awk/run.h
index 813af41d..daa31952 100644
--- a/qse/lib/awk/run.h
+++ b/qse/lib/awk/run.h
@@ -96,8 +96,7 @@ enum qse_awk_unrop_type_t
 	QSE_AWK_UNROP_PLUS,
 	QSE_AWK_UNROP_MINUS,
 	QSE_AWK_UNROP_LNOT,
-	QSE_AWK_UNROP_BNOT,
-	QSE_AWK_UNROP_DEF  /* `, is defined */
+	QSE_AWK_UNROP_BNOT
 };
 
 enum qse_awk_incop_type_t
diff --git a/qse/lib/awk/tree.c b/qse/lib/awk/tree.c
index 0af59bc1..091a9c3d 100644
--- a/qse/lib/awk/tree.c
+++ b/qse/lib/awk/tree.c
@@ -1214,9 +1214,7 @@ void qse_awk_clrpt (qse_awk_t* awk, qse_awk_nde_t* tree)
 				qse_awk_nde_if_t* px = (qse_awk_nde_if_t*)p;
 				qse_awk_clrpt (awk, px->test);
 				qse_awk_clrpt (awk, px->then_part);
-
-				if (px->else_part != QSE_NULL)
-					qse_awk_clrpt (awk, px->else_part);
+				if (px->else_part) qse_awk_clrpt (awk, px->else_part);
 				QSE_AWK_FREE (awk, p);
 				break;
 			}
@@ -1233,13 +1231,9 @@ void qse_awk_clrpt (qse_awk_t* awk, qse_awk_nde_t* tree)
 			case QSE_AWK_NDE_FOR:
 			{
 				qse_awk_nde_for_t* px = (qse_awk_nde_for_t*)p;
-
-				if (px->init != QSE_NULL)
-					qse_awk_clrpt (awk, px->init);
-				if (px->test != QSE_NULL)
-					qse_awk_clrpt (awk, px->test);
-				if (px->incr != QSE_NULL)
-					qse_awk_clrpt (awk, px->incr);
+				if (px->init) qse_awk_clrpt (awk, px->init);
+				if (px->test) qse_awk_clrpt (awk, px->test);
+				if (px->incr) qse_awk_clrpt (awk, px->incr);
 				qse_awk_clrpt (awk, px->body);
 				QSE_AWK_FREE (awk, p);
 				break;
@@ -1267,10 +1261,8 @@ void qse_awk_clrpt (qse_awk_t* awk, qse_awk_nde_t* tree)
 
 			case QSE_AWK_NDE_RETURN:
 			{
-				qse_awk_nde_return_t* px =
-					(qse_awk_nde_return_t*)p;
-				if (px->val != QSE_NULL) 
-					qse_awk_clrpt (awk, px->val);
+				qse_awk_nde_return_t* px = (qse_awk_nde_return_t*)p;
+				if (px->val) qse_awk_clrpt (awk, px->val);
 				QSE_AWK_FREE (awk, p);
 				break;
 			}
@@ -1307,12 +1299,9 @@ void qse_awk_clrpt (qse_awk_t* awk, qse_awk_nde_t* tree)
 			case QSE_AWK_NDE_PRINT:
 			case QSE_AWK_NDE_PRINTF:
 			{
-				qse_awk_nde_print_t* px = 
-					(qse_awk_nde_print_t*)p;
-				if (px->args != QSE_NULL) 
-					qse_awk_clrpt (awk, px->args);
-				if (px->out != QSE_NULL) 
-					qse_awk_clrpt (awk, px->out);
+				qse_awk_nde_print_t* px = (qse_awk_nde_print_t*)p;
+				if (px->args) qse_awk_clrpt (awk, px->args);
+				if (px->out) qse_awk_clrpt (awk, px->out);
 				QSE_AWK_FREE (awk, p);
 				break;
 			}
@@ -1423,8 +1412,7 @@ void qse_awk_clrpt (qse_awk_t* awk, qse_awk_nde_t* tree)
 				qse_awk_nde_var_t* px = (qse_awk_nde_var_t*)p;
 				QSE_ASSERT (px->idx != QSE_NULL);
 				qse_awk_clrpt (awk, px->idx);
-				if (px->id.name.ptr != QSE_NULL)
-					QSE_AWK_FREE (awk, px->id.name.ptr);
+				if (px->id.name.ptr) QSE_AWK_FREE (awk, px->id.name.ptr);
 				QSE_AWK_FREE (awk, p);
 				break;
 			}
@@ -1457,12 +1445,9 @@ void qse_awk_clrpt (qse_awk_t* awk, qse_awk_nde_t* tree)
 
 			case QSE_AWK_NDE_GETLINE:
 			{
-				qse_awk_nde_getline_t* px = 
-					(qse_awk_nde_getline_t*)p;
-				if (px->var != QSE_NULL) 
-					qse_awk_clrpt (awk, px->var);
-				if (px->in != QSE_NULL) 
-					qse_awk_clrpt (awk, px->in);
+				qse_awk_nde_getline_t* px = (qse_awk_nde_getline_t*)p;
+				if (px->var) qse_awk_clrpt (awk, px->var);
+				if (px->in) qse_awk_clrpt (awk, px->in);
 				QSE_AWK_FREE (awk, p);
 				break;
 			}
diff --git a/qse/lib/awk/val.c b/qse/lib/awk/val.c
index 3dbe6350..d1fae342 100644
--- a/qse/lib/awk/val.c
+++ b/qse/lib/awk/val.c
@@ -702,9 +702,8 @@ qse_awk_val_t* qse_awk_rtx_makerefval (
 	}
 	else
 	{
-		val = (qse_awk_val_ref_t*) QSE_AWK_ALLOC (
-			rtx->awk, QSE_SIZEOF(qse_awk_val_ref_t));
-		if (val == QSE_NULL)
+		val = (qse_awk_val_ref_t*)QSE_AWK_ALLOC(rtx->awk, QSE_SIZEOF(qse_awk_val_ref_t));
+		if (!val)
 		{
 			qse_awk_rtx_seterrnum (rtx, QSE_AWK_ENOMEM, QSE_NULL);
 			return QSE_NULL;
@@ -720,14 +719,12 @@ qse_awk_val_t* qse_awk_rtx_makerefval (
 
 	return (qse_awk_val_t*)val;
 }
-qse_awk_val_t* qse_awk_rtx_makefunval (
-	qse_awk_rtx_t* rtx, const qse_awk_fun_t* fun)
+qse_awk_val_t* qse_awk_rtx_makefunval (qse_awk_rtx_t* rtx, const qse_awk_fun_t* fun)
 {
 	qse_awk_val_fun_t* val;
 
-	val = (qse_awk_val_fun_t*) QSE_AWK_ALLOC (
-		rtx->awk, QSE_SIZEOF(qse_awk_val_fun_t));
-	if (val == QSE_NULL)
+	val = (qse_awk_val_fun_t*)QSE_AWK_ALLOC(rtx->awk, QSE_SIZEOF(qse_awk_val_fun_t));
+	if (!val)
 	{
 		qse_awk_rtx_seterrnum (rtx, QSE_AWK_ENOMEM, QSE_NULL);
 		return QSE_NULL;
@@ -870,8 +867,12 @@ void qse_awk_rtx_freeval (qse_awk_rtx_t* rtx, qse_awk_val_t* val, int cache)
 				else QSE_AWK_FREE (rtx->awk, val);
 				break;
 			}
-		}
 
+			case QSE_AWK_VAL_FUN:
+				/* nothing to do */
+				break;
+
+		}
 	}
 }
 
@@ -1008,6 +1009,9 @@ int qse_awk_rtx_valtobool (qse_awk_rtx_t* rtx, const qse_awk_val_t* val)
 			return QSE_HTB_SIZE(((qse_awk_val_map_t*)val)->map) > 0;
 		case QSE_AWK_VAL_REF:
 			return val_ref_to_bool (rtx, (qse_awk_val_ref_t*)val);
+		case QSE_AWK_VAL_FUN:
+			/* return always true */
+			return 1;
 	}
 
 	QSE_ASSERTX (
@@ -1512,6 +1516,11 @@ int qse_awk_rtx_valtostr (qse_awk_rtx_t* rtx, const qse_awk_val_t* v, qse_awk_rt
 		{
 			return val_ref_to_str(rtx, (qse_awk_val_ref_t*)v, out);
 		}
+
+		case QSE_AWK_VAL_FUN:
+		{
+			return qse_awk_rtx_makestrval2(rtx, QSE_T("@@"), 1, ((qse_awk_val_fun_t*)v)->fun->name.ptr, ((qse_awk_val_fun_t*)v)->fun->name.len);
+		}
 	}
 
 
@@ -1742,7 +1751,7 @@ static int val_ref_to_num (qse_awk_rtx_t* rtx, const qse_awk_val_ref_t* ref, qse
 			/* A reference value is not able to point to another 
 			 * refernce value for the way values are represented
 			 * in QSEAWK */
-			QSE_ASSERT (QSE_AWK_RTX_GETVALTYPE (rtx, *xref) != QSE_AWK_VAL_REF); 
+			QSE_ASSERT (QSE_AWK_RTX_GETVALTYPE(rtx, *xref) != QSE_AWK_VAL_REF); 
 
 			/* make a recursive call back to the caller */
 			return qse_awk_rtx_valtonum(rtx, *xref, l, r);
@@ -1804,12 +1813,19 @@ int qse_awk_rtx_valtonum (qse_awk_rtx_t* rtx, const qse_awk_val_t* v, qse_awk_in
 				*l = QSE_HTB_SIZE(((qse_awk_val_map_t*)v)->map);
 				return 0; /* long */
 			}
+			break;
 		}
 
 		case QSE_AWK_VAL_REF:
 		{
 			return val_ref_to_num(rtx, (qse_awk_val_ref_t*)v, l, r);
 		}
+
+		case QSE_AWK_VAL_FUN:
+		{
+			/* TODO: */
+			break;
+		}
 	}
 
 #ifdef DEBUG_VAL
@@ -2131,7 +2147,7 @@ void qse_awk_dprintval (qse_awk_rtx_t* run, qse_awk_val_t* val)
 			break;
 
 		case QSE_AWK_VAL_REX:
-			qse_errputstrf (QSE_T("REX[%s]"), ((qse_awk_val_rex_t*)val)->ptr);
+			qse_errputstrf (QSE_T("/%s/"), ((qse_awk_val_rex_t*)val)->ptr);
 			break;
 
 		case QSE_AWK_VAL_MAP:
@@ -2139,13 +2155,17 @@ void qse_awk_dprintval (qse_awk_rtx_t* run, qse_awk_val_t* val)
 			qse_htb_walk (((qse_awk_val_map_t*)val)->map, print_pair, run);
 			qse_errputstrf (QSE_T("]"));
 			break;
-	
+
 		case QSE_AWK_VAL_REF:
 			qse_errputstrf (QSE_T("REF[id=%d,val="), ((qse_awk_val_ref_t*)val)->id);
 			qse_awk_dprintval (run, *((qse_awk_val_ref_t*)val)->adr);
 			qse_errputstrf (QSE_T("]"));
 			break;
 
+		case QSE_AWK_VAL_FUN:
+			qse_errputstrf (QSE_T("@@%.*s"), (int)((qse_awk_val_fun_t*)val)->fun->name.len, ((qse_awk_val_fun_t*)val)->fun->name.ptr);
+			break;
+
 		default:
 			qse_errputstrf (QSE_T("**** INTERNAL ERROR - INVALID VALUE TYPE ****\n"));
 	}