diff --git a/qse/cmd/awk/awk.c b/qse/cmd/awk/awk.c
index 1cfb4c1e..674f59d3 100644
--- a/qse/cmd/awk/awk.c
+++ b/qse/cmd/awk/awk.c
@@ -1,5 +1,5 @@
 /*
- * $Id: awk.c 76 2009-02-22 14:18:06Z hyunghwan.chung $
+ * $Id: awk.c 85 2009-02-26 10:56:12Z hyunghwan.chung $
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -549,7 +549,7 @@ static qse_awk_t* open_awk (void)
 {
 	qse_awk_t* awk;
 
-	awk = qse_awk_openstd ();
+	awk = qse_awk_openstd (0);
 	if (awk == QSE_NULL)
 	{
 		qse_printf (QSE_T("ERROR: cannot open awk\n"));
diff --git a/qse/include/qse/awk/awk.h b/qse/include/qse/awk/awk.h
index 63599bef..7b73cabd 100644
--- a/qse/include/qse/awk/awk.h
+++ b/qse/include/qse/awk/awk.h
@@ -1,5 +1,5 @@
 /*
- * $Id: awk.h 79 2009-02-24 03:57:28Z hyunghwan.chung $
+ * $Id: awk.h 85 2009-02-26 10:56:12Z hyunghwan.chung $
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -49,9 +49,6 @@ typedef struct qse_awk_t     qse_awk_t;
 typedef struct qse_awk_rtx_t qse_awk_rtx_t; /* (R)untime con(T)e(X)t */
 /******/
 
-/* this is not a value. it is just a value holder */
-typedef struct qse_awk_val_chunk_t qse_awk_val_chunk_t;
-
 #if QSE_SIZEOF_INT == 2
 #	define QSE_AWK_VAL_HDR \
 		unsigned int type: 3; \
@@ -181,11 +178,6 @@ struct qse_awk_val_ref_t
 };
 typedef struct qse_awk_val_ref_t  qse_awk_val_ref_t;
 
-typedef struct qse_awk_prm_t qse_awk_prm_t;
-typedef struct qse_awk_sio_t qse_awk_sio_t;
-typedef struct qse_awk_rio_t qse_awk_rio_t;
-typedef struct qse_awk_riod_t qse_awk_riod_t;
-typedef struct qse_awk_rcb_t qse_awk_rcb_t;
 
 typedef qse_real_t (*qse_awk_pow_t) (
 	qse_awk_t* awk,
@@ -213,6 +205,11 @@ typedef qse_cint_t (*qse_awk_toccls_t) (
 	qse_ccls_id_t type
 );
 
+/****e* AWK/qse_awk_sio_cmd_t
+ * NAME
+ *  qse_awk_sio_cmd_t - define source IO commands
+ * SYNOPSIS
+ */
 enum qse_awk_sio_cmd_t
 {
 	QSE_AWK_SIO_OPEN   = 0,
@@ -220,8 +217,8 @@ enum qse_awk_sio_cmd_t
 	QSE_AWK_SIO_READ   = 2,
 	QSE_AWK_SIO_WRITE  = 3
 };
-
 typedef enum qse_awk_sio_cmd_t qse_awk_sio_cmd_t;
+/******/
 
 /****t* AWK/qse_awk_siof_t
  * NAME
@@ -245,23 +242,8 @@ enum qse_awk_rio_cmd_t
 	QSE_AWK_RIO_FLUSH  = 4,
 	QSE_AWK_RIO_NEXT   = 5  
 };
-
 typedef enum qse_awk_rio_cmd_t qse_awk_rio_cmd_t;
 
-/****f* AWK/qse_awk_riof_t
- * NAME
- *  qse_awk_riof_t - define a runtime IO function
- * SYNOPSIS
- */
-typedef qse_ssize_t (*qse_awk_riof_t) (
-	qse_awk_rtx_t*    rtx,
-	qse_awk_rio_cmd_t cmd, 
-	qse_awk_riod_t*   riod,
-	qse_char_t*       data,
-	qse_size_t        count
-);
-/******/
-
 /****f* AWK/qse_awk_riod_t
  * NAME
  *  qse_awk_riod_f - define the data passed to a rio function 
@@ -291,10 +273,31 @@ struct qse_awk_riod_t
 		qse_bool_t eos;
 	} out;
 
-	qse_awk_riod_t* next;
+	struct qse_awk_riod_t* next;
 };
+typedef struct qse_awk_riod_t qse_awk_riod_t;
 /******/
 
+/****f* AWK/qse_awk_riof_t
+ * NAME
+ *  qse_awk_riof_t - define a runtime IO function
+ * SYNOPSIS
+ */
+typedef qse_ssize_t (*qse_awk_riof_t) (
+	qse_awk_rtx_t*    rtx,
+	qse_awk_rio_cmd_t cmd, 
+	qse_awk_riod_t*   riod,
+	qse_char_t*       data,
+	qse_size_t        count
+);
+/******/
+
+
+/****s* AWK/qse_awk_prm_t
+ * NAME
+ *  qse_awk_prm_t - define primitive functions
+ * SYNOPSIS
+ */
 struct qse_awk_prm_t
 {
 	qse_awk_pow_t     pow;
@@ -333,20 +336,41 @@ struct qse_awk_prm_t
 	);
 #endif
 };
+typedef struct qse_awk_prm_t qse_awk_prm_t;
+/******/
 
+/****s* AWK/qse_awk_sio_t
+ * NAME
+ *  qse_awk_sio_t - define source code IO
+ * SYNOPSIS
+ */
 struct qse_awk_sio_t
 {
 	qse_awk_siof_t in;
 	qse_awk_siof_t out;
 };
+typedef struct qse_awk_sio_t qse_awk_sio_t;
+/******/
 
+/****s* AWK/qse_awk_rio_t
+ * NAME
+ *  qse_awk_rio_t - define runtime IO
+ * SYNOPSIS
+ */
 struct qse_awk_rio_t
 {
 	qse_awk_riof_t pipe;
 	qse_awk_riof_t file;
 	qse_awk_riof_t console;
 };
+typedef struct qse_awk_rio_t qse_awk_rio_t;
+/******/
 
+/****s* AWK/qse_awk_rcb_t
+ * NAME
+ *  qse_awk_rcb_t - define runtime callbacks
+ * SYNOPSIS
+ */
 struct qse_awk_rcb_t
 {
 	int (*on_enter) (
@@ -360,6 +384,8 @@ struct qse_awk_rcb_t
 
 	void* data;
 };
+typedef struct qse_awk_rcb_t qse_awk_rcb_t;
+/******/
 
 /* various options */
 enum qse_awk_option_t
diff --git a/qse/include/qse/awk/std.h b/qse/include/qse/awk/std.h
index 3660d092..6218fe58 100644
--- a/qse/include/qse/awk/std.h
+++ b/qse/include/qse/awk/std.h
@@ -1,5 +1,5 @@
 /*
- * $Id: std.h 84 2009-02-25 10:35:22Z hyunghwan.chung $
+ * $Id: std.h 85 2009-02-26 10:56:12Z hyunghwan.chung $
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -89,7 +89,17 @@ extern "C" {
  * SYNOPSIS
  */
 qse_awk_t* qse_awk_openstd (
-	void
+	qse_size_t xtnsize
+);
+/******/
+
+/****f* AWK/qse_awk_getxtnstd
+ * NAME
+ *  qse_awk_getxtnstd - get the pointer to extension space
+ * SYNOPSIS
+ */
+void* qse_awk_getxtnstd (
+	qse_awk_t* awk
 );
 /******/
 
diff --git a/qse/lib/awk/awk.c b/qse/lib/awk/awk.c
index 0220251f..826c41fb 100644
--- a/qse/lib/awk/awk.c
+++ b/qse/lib/awk/awk.c
@@ -1,5 +1,5 @@
 /*
- * $Id: awk.c 75 2009-02-22 14:10:34Z hyunghwan.chung $ 
+ * $Id: awk.c 85 2009-02-26 10:56:12Z hyunghwan.chung $ 
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -78,10 +78,20 @@ qse_awk_t* qse_awk_open (qse_mmgr_t* mmgr, qse_size_t xtn, qse_awk_prm_t* prm)
 	awk->mmgr = mmgr;
 
 	/* progagate the primitive functions */
+	QSE_ASSERT (prm          != QSE_NULL);
 	QSE_ASSERT (prm->pow     != QSE_NULL);
 	QSE_ASSERT (prm->sprintf != QSE_NULL);
 	QSE_ASSERT (prm->isccls  != QSE_NULL);
 	QSE_ASSERT (prm->toccls  != QSE_NULL);
+	if (prm          == QSE_NULL || 
+	    prm->pow     == QSE_NULL ||
+	    prm->sprintf == QSE_NULL ||
+	    prm->isccls  == QSE_NULL ||
+	    prm->toccls  == QSE_NULL)
+	{
+		QSE_AWK_FREE (awk, awk);
+		return QSE_NULL;
+	}
 	awk->prm = *prm;
 
 	/* build a character classifier from the primitive functions */
diff --git a/qse/lib/awk/parse.c b/qse/lib/awk/parse.c
index 0aeef62f..75bab391 100644
--- a/qse/lib/awk/parse.c
+++ b/qse/lib/awk/parse.c
@@ -1,5 +1,5 @@
 /*
- * $Id: parse.c 75 2009-02-22 14:10:34Z hyunghwan.chung $
+ * $Id: parse.c 85 2009-02-26 10:56:12Z hyunghwan.chung $
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -469,9 +469,16 @@ int qse_awk_parse (qse_awk_t* awk, qse_awk_sio_t* sio)
 {
 	int n;
 
-	QSE_ASSERTX (
-		sio != QSE_NULL && sio->in != QSE_NULL,
+	QSE_ASSERTX (sio != QSE_NULL ,
+		"the source code istream must be provided");
+	QSE_ASSERTX (sio->in != QSE_NULL,
 		"the source code input stream must be provided at least");
+	if (sio == QSE_NULL || sio->in == QSE_NULL)
+	{
+		SETERR (awk, QSE_AWK_EINVAL);
+		return -1;
+	}
+
 	QSE_ASSERT (awk->parse.depth.cur.loop == 0);
 	QSE_ASSERT (awk->parse.depth.cur.expr == 0);
 
diff --git a/qse/lib/awk/std.c b/qse/lib/awk/std.c
index 81c7017e..a85b4bde 100644
--- a/qse/lib/awk/std.c
+++ b/qse/lib/awk/std.c
@@ -1,5 +1,5 @@
 /*
- * $Id: std.c 84 2009-02-25 10:35:22Z hyunghwan.chung $
+ * $Id: std.c 85 2009-02-26 10:56:12Z hyunghwan.chung $
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -138,7 +138,7 @@ static qse_cint_t custom_awk_toccls (
 
 static int add_functions (qse_awk_t* awk);
 
-qse_awk_t* qse_awk_openstd (void)
+qse_awk_t* qse_awk_openstd (qse_size_t xtnsize)
 {
 	qse_awk_t* awk;
 	qse_awk_prm_t prm;
@@ -150,7 +150,8 @@ qse_awk_t* qse_awk_openstd (void)
 	prm.toccls  = custom_awk_toccls;
 
 	/* create an object */
-	awk = qse_awk_open (QSE_MMGR_GETDFL(), QSE_SIZEOF(xtn_t), &prm);
+	awk = qse_awk_open (
+		QSE_MMGR_GETDFL(), QSE_SIZEOF(xtn_t) + xtnsize, &prm);
 	if (awk == QSE_NULL) return QSE_NULL;
 
 	/* initialize extension */
@@ -167,6 +168,11 @@ qse_awk_t* qse_awk_openstd (void)
 	return awk;
 }
 
+void* qse_awk_getxtnstd (qse_awk_t* awk)
+{
+	return (void*)((xtn_t*)QSE_XTN(awk) + 1);
+}
+
 /*** PARSESTD ***/
 
 static qse_ssize_t sf_in (
diff --git a/qse/lib/awk/val.c b/qse/lib/awk/val.c
index a99a0ade..ade7b4a0 100644
--- a/qse/lib/awk/val.c
+++ b/qse/lib/awk/val.c
@@ -1,5 +1,5 @@
 /*
- * $Id: val.c 78 2009-02-23 14:03:28Z hyunghwan.chung $
+ * $Id: val.c 85 2009-02-26 10:56:12Z hyunghwan.chung $
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -22,33 +22,7 @@
 #include <qse/utl/stdio.h>
 #endif
 
-#define CHUNKSIZE 100
-
-typedef struct qse_awk_val_ichunk_t qse_awk_val_ichunk_t;
-typedef struct qse_awk_val_rchunk_t qse_awk_val_rchunk_t;
-
-struct qse_awk_val_chunk_t
-{
-        qse_awk_val_chunk_t* next;
-};
-
-struct qse_awk_val_ichunk_t
-{
-	qse_awk_val_chunk_t* next;
-	/* make sure that it has the same fields as 
-	   qse_awk_val_chunk_t up to this point */
-
-	qse_awk_val_int_t slot[CHUNKSIZE];
-};
-
-struct qse_awk_val_rchunk_t
-{
-	qse_awk_val_chunk_t* next;
-	/* make sure that it has the same fields as 
-	   qse_awk_val_chunk_t up to this point */
-
-	qse_awk_val_real_t slot[CHUNKSIZE];
-};
+#define CHUNKSIZE QSE_AWK_VAL_CHUNK_SIZE
 
 static qse_char_t* str_to_str (
 	qse_awk_rtx_t* run, const qse_char_t* str, qse_size_t str_len,
diff --git a/qse/lib/awk/val.h b/qse/lib/awk/val.h
index f404b140..ade31923 100644
--- a/qse/lib/awk/val.h
+++ b/qse/lib/awk/val.h
@@ -1,5 +1,5 @@
 /*
- * $Id: val.h 75 2009-02-22 14:10:34Z hyunghwan.chung $
+ * $Id: val.h 85 2009-02-26 10:56:12Z hyunghwan.chung $
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -19,6 +19,35 @@
 #ifndef _QSE_LIB_AWK_VAL_H_
 #define _QSE_LIB_AWK_VAL_H_
 
+#define QSE_AWK_VAL_CHUNK_SIZE 100
+
+typedef struct qse_awk_val_chunk_t qse_awk_val_chunk_t;
+typedef struct qse_awk_val_ichunk_t qse_awk_val_ichunk_t;
+typedef struct qse_awk_val_rchunk_t qse_awk_val_rchunk_t;
+
+struct qse_awk_val_chunk_t
+{
+        qse_awk_val_chunk_t* next;
+};
+
+struct qse_awk_val_ichunk_t
+{
+	qse_awk_val_chunk_t* next;
+	/* make sure that it has the same fields as 
+	   qse_awk_val_chunk_t up to this point */
+
+	qse_awk_val_int_t slot[QSE_AWK_VAL_CHUNK_SIZE];
+};
+
+struct qse_awk_val_rchunk_t
+{
+	qse_awk_val_chunk_t* next;
+	/* make sure that it has the same fields as 
+	   qse_awk_val_chunk_t up to this point */
+
+	qse_awk_val_real_t slot[QSE_AWK_VAL_CHUNK_SIZE];
+};
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/qse/test/awk/awk01.c b/qse/test/awk/awk01.c
index 486808db..73c6b90b 100644
--- a/qse/test/awk/awk01.c
+++ b/qse/test/awk/awk01.c
@@ -1,5 +1,5 @@
 /*
- * $Id: awk01.c 76 2009-02-22 14:18:06Z hyunghwan.chung $ 
+ * $Id: awk01.c 85 2009-02-26 10:56:12Z hyunghwan.chung $ 
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -44,7 +44,7 @@ int main ()
 	qse_awk_parsestd_in_t psin;
 	int ret;
 
-	awk = qse_awk_openstd ();
+	awk = qse_awk_openstd (0);
 	if (awk == QSE_NULL)  
 	{
 		qse_fprintf (QSE_STDERR, QSE_T("error: cannot open awk\n"));
diff --git a/qse/test/awk/awk02.c b/qse/test/awk/awk02.c
index c64075fe..31559892 100644
--- a/qse/test/awk/awk02.c
+++ b/qse/test/awk/awk02.c
@@ -1,5 +1,5 @@
 /*
- * $Id: awk02.c 76 2009-02-22 14:18:06Z hyunghwan.chung $ 
+ * $Id: awk02.c 85 2009-02-26 10:56:12Z hyunghwan.chung $ 
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -50,7 +50,7 @@ int main ()
 
 	int ret;
 
-	awk = qse_awk_openstd ();
+	awk = qse_awk_openstd (0);
 	if (awk == QSE_NULL)  
 	{
 		qse_fprintf (QSE_STDERR, QSE_T("error: cannot open awk\n"));
diff --git a/qse/test/awk/awk03.c b/qse/test/awk/awk03.c
index b9168beb..60d2f0c6 100644
--- a/qse/test/awk/awk03.c
+++ b/qse/test/awk/awk03.c
@@ -1,5 +1,5 @@
 /*
- * $Id: awk03.c 76 2009-02-22 14:18:06Z hyunghwan.chung $
+ * $Id: awk03.c 85 2009-02-26 10:56:12Z hyunghwan.chung $
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -54,7 +54,7 @@ int main ()
 	int ret, i;
 
 	/* create a main processor */
-	awk = qse_awk_openstd ();
+	awk = qse_awk_openstd (0);
 	if (awk == QSE_NULL)  
 	{
 		qse_fprintf (QSE_STDERR, QSE_T("error: cannot open awk\n"));
diff --git a/qse/test/awk/awk04.c b/qse/test/awk/awk04.c
index cbfcba42..91be4c5a 100644
--- a/qse/test/awk/awk04.c
+++ b/qse/test/awk/awk04.c
@@ -1,5 +1,5 @@
 /*
- * $Id: awk04.c 76 2009-02-22 14:18:06Z hyunghwan.chung $
+ * $Id: awk04.c 85 2009-02-26 10:56:12Z hyunghwan.chung $
  *
    Copyright 2006-2009 Chung, Hyung-Hwan.
 
@@ -44,7 +44,7 @@ int main ()
 	int ret, i;
 
 	/* create a main processor */
-	awk = qse_awk_openstd ();
+	awk = qse_awk_openstd (0);
 	if (awk == QSE_NULL)  
 	{
 		qse_fprintf (QSE_STDERR, QSE_T("error: cannot open awk\n"));