diff --git a/stix/lib/comp.c b/stix/lib/comp.c
index 29188dc..5a49e24 100644
--- a/stix/lib/comp.c
+++ b/stix/lib/comp.c
@@ -219,7 +219,7 @@ static STIX_INLINE int is_closing_char (stix_cint_t c)
 #define ADD_TOKEN_STR(fsc,s) \
 	do { if (add_token_str (fsc, s) == -1) return -1; } while (0)
 
-static STIX_INLINE int add_token_char (stix_t* fsc, stix_char_t c)
+static STIX_INLINE int add_token_char (stix_t* fsc, stix_uch_t c)
 {
 	if (fsc->tok.name.len >= STIX_COUNTOF(fsc->tok.buf) - 1)
 	{
@@ -232,7 +232,7 @@ static STIX_INLINE int add_token_char (stix_t* fsc, stix_char_t c)
 	return 0;
 }
 
-static STIX_INLINE int add_token_str (stix_t* fsc, const stix_char_t* str)
+static STIX_INLINE int add_token_str (stix_t* fsc, const stix_uch_t* str)
 {
 	stix_size_t len;
 
@@ -247,49 +247,52 @@ static STIX_INLINE int add_token_str (stix_t* fsc, const stix_char_t* str)
 	fsc->tok.name.len += stix_strcpy (&fsc->tok.buf[fsc->tok.name.len], str);
 	return 0;
 }
+#endif
 
-static int get_char (stix_t* fsc)
+static int get_char (stix_t* stix)
 {
 	stix_ssize_t n;
 
-	if (fsc->sio.inp->b.pos >= fsc->sio.inp->b.len)
+	if (stix->c->curinp->b.pos >= stix->c->curinp->b.len)
 	{
-		n = fsc->sio.impl (fsc, STIX_FSC_IO_READ, fsc->sio.inp);
+		n = stix->c->impl (stix, STIX_IO_READ, stix->c->curinp);
 		if (n <= -1) return -1;
 
 		if (n == 0)
 		{
-			fsc->sio.inp->lxc.c = STIX_CHAR_EOF;
-			fsc->sio.inp->lxc.line = fsc->sio.inp->line;
-			fsc->sio.inp->lxc.colm = fsc->sio.inp->colm;
-			fsc->sio.inp->lxc.file = fsc->sio.inp->name;
-			fsc->sio.lxc = fsc->sio.inp->lxc;
-			return 0;
+//			stix->c->curinp->lxc.c = STIX_CHAR_EOF;
+			stix->c->curinp->lxc.c = 0;
+			stix->c->curinp->lxc.line = stix->c->curinp->line;
+			stix->c->curinp->lxc.colm = stix->c->curinp->colm;
+			stix->c->curinp->lxc.file = stix->c->curinp->name;
+			stix->c->lxc = stix->c->curinp->lxc;
+			return 0; /* indicate that EOF has been read */
 		}
 
-		fsc->sio.inp->b.pos = 0;
-		fsc->sio.inp->b.len = n;	
+		stix->c->curinp->b.pos = 0;
+		stix->c->curinp->b.len = n;
 	}
 
-	if (fsc->sio.inp->lxc.c == STIX_T('\n'))
+	if (stix->c->curinp->lxc.c == '\n')
 	{
 		/* if the previous charater was a newline,
 		 * increment the line counter and reset column to 1.
 		 * incrementing it line number here instead of
 		 * updating inp->lxc causes the line number for
 		 * TOK_EOF to be the same line as the lxc newline. */
-		fsc->sio.inp->line++;
-		fsc->sio.inp->colm = 1;
+		stix->c->curinp->line++;
+		stix->c->curinp->colm = 1;
 	}
-	
-	fsc->sio.inp->lxc.c = fsc->sio.inp->buf[fsc->sio.inp->b.pos++];
-	fsc->sio.inp->lxc.line = fsc->sio.inp->line;
-	fsc->sio.inp->lxc.colm = fsc->sio.inp->colm++;
-	fsc->sio.inp->lxc.file = fsc->sio.inp->name;
-	fsc->sio.lxc = fsc->sio.inp->lxc;
-	return 0;
+
+	stix->c->curinp->lxc.c = stix->c->curinp->buf[stix->c->curinp->b.pos++];
+	stix->c->curinp->lxc.line = stix->c->curinp->line;
+	stix->c->curinp->lxc.colm = stix->c->curinp->colm++;
+	stix->c->curinp->lxc.file = stix->c->curinp->name;
+	stix->c->lxc = stix->c->curinp->lxc;
+	return 1; /* indicate that a normal character has been read */
 }
 
+#if 0
 static int skip_spaces (stix_t* fsc)
 {
 	while (STIX_ISSPACE(fsc->sio.lxc.c)) GET_CHAR (fsc);
@@ -653,9 +656,9 @@ retry:
 			else 
 			{
 				stix_cstr_t ea;
-				stix_char_t cc;
+				stix_uch_t cc;
 
-				cc = (stix_char_t)c;
+				cc = (stix_uch_t)c;
 				ea.ptr = &cc;
 				ea.len = 1;
 
@@ -685,17 +688,17 @@ static int begin_include (stix_t* fsc)
 	stix_ioarg_t* arg;
 	stix_link_t* link;
 
-	link = (stix_link_t*) stix_callocmem (fsc, STIX_SIZEOF(*link) + STIX_SIZEOF(stix_char_t) * (fsc->tok.name.len + 1));
+	link = (stix_link_t*) stix_callocmem (fsc, STIX_SIZEOF(*link) + STIX_SIZEOF(stix_uch_t) * (fsc->tok.name.len + 1));
 	if (link == STIX_NULL) goto oops;
 
-	stix_strcpy ((stix_char_t*)(link + 1), fsc->tok.name.ptr); 
+	stix_strcpy ((stix_uch_t*)(link + 1), fsc->tok.name.ptr); 
 	link->link = fsc->sio_names;
 	fsc->sio_names = link;
 
 	arg = (stix_ioarg_t*) stix_callocmem (fsc, STIX_SIZEOF(*arg));
 	if (arg == STIX_NULL) goto oops;
 
-	arg->name = (const stix_char_t*)(link + 1);
+	arg->name = (const stix_uch_t*)(link + 1);
 	arg->line = 1;
 	arg->colm = 1;
 	arg->prev = fsc->sio.inp;
@@ -777,7 +780,7 @@ static STIX_INLINE int is_tok_pseudovar (stix_t* fsc)
 	        stix_strequal(fsc->tok.name.ptr, STIX_T("false")));
 }
 
-static STIX_INLINE int is_tok_binsel (stix_t* fsc, const stix_char_t* sel)
+static STIX_INLINE int is_tok_binsel (stix_t* fsc, const stix_uch_t* sel)
 {
 	return fsc->tok.type == STIX_FSC_TOK_BINSEL && 
 	       stix_strequal (fsc->tok.name.ptr, sel);
@@ -848,7 +851,7 @@ static STIX_INLINE int is_tok_binsel (stix_t* fsc, const stix_char_t* sel)
 #endif
 
 static STIX_INLINE int emit_code_test (
-	stix_t* fsc, const stix_char_t* high, const stix_char_t* low)
+	stix_t* fsc, const stix_uch_t* high, const stix_uch_t* low)
 {
 wprintf (L"CODE: %s %s\n", high, low);
 	return 0;
@@ -1037,7 +1040,7 @@ static int __add_literal (stix_t* fsc, stix_word_t literal)
 	return fsc->literal_count - 1;
 }
 
-static int __add_character_literal (stix_t* fsc, stix_char_t ch)
+static int __add_character_literal (stix_t* fsc, stix_uch_t ch)
 {
 	stix_word_t i, c, literal;
 	stix_vm_t* stx = fsc->stx;
@@ -1056,7 +1059,7 @@ static int __add_character_literal (stix_t* fsc, stix_char_t ch)
 }
 
 static int __add_string_literal (
-	stix_t* fsc, const stix_char_t* str, stix_word_t size)
+	stix_t* fsc, const stix_uch_t* str, stix_word_t size)
 {
 	stix_word_t i, c, literal;
 	stix_vm_t* stx = fsc->stx;
@@ -1077,7 +1080,7 @@ static int __add_string_literal (
 }
 
 static int __add_symbol_literal (
-	stix_t* fsc, const stix_char_t* str, stix_word_t size)
+	stix_t* fsc, const stix_uch_t* str, stix_word_t size)
 {
 	stix_vm_t* stx = fsc->stx;
 	return __add_literal (fsc, stix_new_symbolx(stx, str, size));
@@ -1210,7 +1213,7 @@ static int parse_expression (stix_t* fsc)
 	stix_vm_t* stx = fsc->stx;
 
 	if (fsc->tok.type == STIX_FSC_TOK_IDENT) {
-		stix_char_t* ident = stix_tok_yield (&fsc->tok, 0);
+		stix_uch_t* ident = stix_tok_yield (&fsc->tok, 0);
 		if (ident == STIX_NULL) {
 			fsc->errnum = STIX_FSC_ERROR_MEMORY;
 			return -1;
@@ -1242,7 +1245,7 @@ static int parse_expression (stix_t* fsc)
 }
 
 static int parse_basic_expression (
-	stix_t* fsc, const stix_char_t* ident)
+	stix_t* fsc, const stix_uch_t* ident)
 {
 	/*
 	 * <basic expression> ::= <primary> [<messages> <cascaded messages>]
@@ -1259,7 +1262,7 @@ static int parse_basic_expression (
 }
 
 static int parse_assignment (
-	stix_t* fsc, const stix_char_t* target)
+	stix_t* fsc, const stix_uch_t* target)
 {
 	/*
 	 * <assignment> ::= <assignment target> assignmentOperator <expression>
@@ -1304,7 +1307,7 @@ static int parse_assignment (
 }
 
 static int parse_primary (
-	stix_t* fsc, const stix_char_t* ident, int* is_super)
+	stix_t* fsc, const stix_uch_t* ident, int* is_super)
 {
 	/*
 	 * <primary> ::=
@@ -1389,7 +1392,7 @@ static int parse_primary (
 }
 
 static int parse_primary_ident (
-	stix_t* fsc, const stix_char_t* ident, int* is_super)
+	stix_t* fsc, const stix_uch_t* ident, int* is_super)
 {
 	stix_word_t i;
 	stix_vm_t* stx = fsc->stx;
@@ -1616,7 +1619,7 @@ static int parse_binary_message (stix_t* fsc, int is_super)
 
 	while (fsc->tok.type == STIX_FSC_TOK_BINSEL) 
 	{
-		stix_char_t* op = stix_tok_yield (&fsc->tok, 0);
+		stix_uch_t* op = stix_tok_yield (&fsc->tok, 0);
 		if (op == STIX_NULL) {
 			fsc->errnum = STIX_FSC_ERROR_MEMORY;
 			return -1;
@@ -1707,11 +1710,11 @@ static int parse_method (stix_t* fsc, stix_word_t method_class, void* input)
 
 #endif
 
-static int get_class_type (const stix_char_t* str, class_type_t* type)
+static int get_class_type (const stix_uch_t* str, class_type_t* type)
 {
 	static struct 
 	{
-		stix_char_t* word;
+		stix_uch_t* word;
 		class_type_t type;
 	} tab[] = 
 	{
@@ -1735,11 +1738,11 @@ static int get_class_type (const stix_char_t* str, class_type_t* type)
 	return -1;
 }
 
-static int get_vardef_type (const stix_char_t* str, vardef_type_t* type)
+static int get_vardef_type (const stix_uch_t* str, vardef_type_t* type)
 {
 	static struct 
 	{
-		stix_char_t* word;
+		stix_uch_t* word;
 		class_type_t type;
 	} tab[] = 
 	{
@@ -2254,13 +2257,20 @@ int stix_compile (stix_t* stix, stix_ioimpl_t io)
 	stix->c->arg.line = 1;
 	stix->c->arg.colm = 1;
 	stix->c->curinp = &stix->c->arg;
-	clear_sio_names (stix);
+//	clear_sio_names (stix);
 
 	/* open the top-level stream */
 	n = stix->c->impl (stix, STIX_IO_OPEN, stix->c->curinp);
 	if (n <= -1) return -1;
 
-	if (compile_stream (stix) <= -1) goto oops;
+//	if (compile_stream (stix) <= -1) goto oops;
+	while (get_char(stix) > 0)
+	{
+		stix_bch_t buf[16];
+		stix_size_t len;
+		len = stix_uctoutf8 (stix->c->curinp->lxc.c, buf, STIX_COUNTOF(buf));
+		printf ("%.*s", (int)len, buf);
+	}
 
 	/* close the stream */
 	STIX_ASSERT (stix->c->curinp == &stix->c->arg);
diff --git a/stix/lib/ignite.c b/stix/lib/ignite.c
index 059ea7a..4751f2f 100644
--- a/stix/lib/ignite.c
+++ b/stix/lib/ignite.c
@@ -183,7 +183,7 @@ static int ignite_3 (stix_t* stix)
 	static struct symbol_name_t
 	{
 		stix_oow_t len;
-		stix_char_t str[16];
+		stix_uch_t str[16];
 	} symnames[] = {
 		{  4, { 'S','t','i','x'                                                  } },
 		{  6, { 'O','b','j','e','c','t'                                          } },
diff --git a/stix/lib/main.c b/stix/lib/main.c
index 2a34d9d..a26b8bf 100644
--- a/stix/lib/main.c
+++ b/stix/lib/main.c
@@ -28,7 +28,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-
+#include <string.h>
 
 typedef struct xtn_t xtn_t;
 struct xtn_t
@@ -64,31 +64,41 @@ static stix_mmgr_t sys_mmgr =
 };
 
 
-static STIX_INLINE stix_oow_t open_input (stix_t* stix, stix_ioarg_t* arg)
+static STIX_INLINE stix_ssize_t open_input (stix_t* stix, stix_ioarg_t* arg)
 {
 	if (arg->includer)
 	{
 		/* includee */
-		xtn_t* xtn = stix_getxtn(stix);
+		stix_bch_t bcs[1024]; /* TODO: right buffer size */
+		stix_size_t bcslen = STIX_COUNTOF(bcs);
+		stix_size_t ucslen = ~(stix_size_t)0;
 
-		arg->handle = fopen (xtn->source_path, "r");
-		if (!arg->handle)
+		if (stix_ucstoutf8 (arg->name, &ucslen, bcs, &bcslen) <= -1)
 		{
-			stix_seterrnum (stix, STIX_EIOERR);
+			stix_seterrnum (stix, STIX_EECERR);
 			return -1;
 		}
 	}
 	else
 	{
 		/* main stream */
-		/*char tmp[PATH_MAX];*/
+		xtn_t* xtn = stix_getxtn(stix);
+		arg->handle = fopen (xtn->source_path, "r");
 	}
+
+	if (!arg->handle)
+	{
+		stix_seterrnum (stix, STIX_EIOERR);
+		return -1;
+	}
+
+	return 0;
 }
 
-static STIX_INLINE stix_oow_t read_input (stix_t* stix, stix_ioarg_t* arg)
+static STIX_INLINE stix_ssize_t read_input (stix_t* stix, stix_ioarg_t* arg)
 {
 	xtn_t* xtn = stix_getxtn(stix);
-	stix_size_t n, bcslen, cslen;
+	stix_size_t n, bcslen, ucslen, remlen;
 	int x;
 
 	STIX_ASSERT (arg->handle != STIX_NULL);
@@ -100,32 +110,32 @@ static STIX_INLINE stix_oow_t read_input (stix_t* stix, stix_ioarg_t* arg)
 			stix_seterrnum (stix, STIX_EIOERR);
 			return -1;
 		}
-
-		
 	}
 
 	xtn->bchar_len += n;
 	bcslen = xtn->bchar_len;
-	cslen = STIX_COUNTOF(arg->buf);
-	x = stix_utf8toucs (xtn->bchar_buf, &bcslen, arg->buf, &cslen);
-	if (x == -2)
-	{
-		/* buffer to small */
-	}
-	if (x <= -1)
+	ucslen = STIX_COUNTOF(arg->buf);
+	x = stix_utf8toucs (xtn->bchar_buf, &bcslen, arg->buf, &ucslen);
+	if (x <= -1 && ucslen <= 0)
 	{
+		stix_seterrnum (stix, STIX_EECERR);
+		return -1;
 	}
+
+	remlen = xtn->bchar_len - bcslen;
+	if (remlen > 0) memmove (xtn->bchar_buf, &xtn->bchar_buf[bcslen], remlen);
+	xtn->bchar_len = remlen;
+	return ucslen;
 }
 
-static STIX_INLINE stix_oow_t close_input (stix_t* stix, stix_ioarg_t* arg)
+static STIX_INLINE stix_ssize_t close_input (stix_t* stix, stix_ioarg_t* arg)
 {
 	STIX_ASSERT (arg->handle != STIX_NULL);
 	fclose (arg->handle);
 	return 0;
 }
-/* TODO: IMPLEMENT PROPER INPUT HANDLER */
 
-static stix_oow_t input_handler (stix_t* stix, stix_iocmd_t cmd, stix_ioarg_t* arg)
+static stix_ssize_t input_handler (stix_t* stix, stix_iocmd_t cmd, stix_ioarg_t* arg)
 {
 	switch (cmd)
 	{
@@ -217,8 +227,8 @@ int main (int argc, char* argv[])
 	}
 
 {
-stix_char_t x[] = { 'S', 't', 'r', 'i', 'n', 'g', '\0' };
-stix_char_t y[] = { 'S', 'y', 'm', 'b', 'o', 'l', '\0' };
+stix_uch_t x[] = { 'S', 't', 'r', 'i', 'n', 'g', '\0' };
+stix_uch_t y[] = { 'S', 'y', 'm', 'b', 'o', 'l', '\0' };
 stix_oop_t a, b;
 
 a = stix_makesymbol (stix, x, 6);
diff --git a/stix/lib/memo.txt b/stix/lib/memo.txt
index 6abbd97..1fdded5 100644
--- a/stix/lib/memo.txt
+++ b/stix/lib/memo.txt
@@ -617,4 +617,5 @@ Single line comment
 #! comment text (easy handling to skip hash bang)
 
 Multi-line comments - double quoted as in smalltalk
-" comment text "
+" comment text 설명이라지요. "
+
diff --git a/stix/lib/obj.c b/stix/lib/obj.c
index 213ba7c..5afe2fc 100644
--- a/stix/lib/obj.c
+++ b/stix/lib/obj.c
@@ -114,9 +114,9 @@ static stix_oop_t alloc_numeric_array (stix_t* stix, const void* ptr, stix_oow_t
 	return hdr;
 }
 
-stix_oop_t stix_alloccharobj (stix_t* stix, const stix_char_t* ptr, stix_oow_t len)
+stix_oop_t stix_alloccharobj (stix_t* stix, const stix_uch_t* ptr, stix_oow_t len)
 {
-	return alloc_numeric_array (stix, ptr, len, STIX_OBJ_TYPE_CHAR, STIX_SIZEOF(stix_char_t), 1);
+	return alloc_numeric_array (stix, ptr, len, STIX_OBJ_TYPE_CHAR, STIX_SIZEOF(stix_uch_t), 1);
 }
 
 stix_oop_t stix_allocuint8obj (stix_t* stix, const stix_uint8_t* ptr, stix_oow_t len)
diff --git a/stix/lib/stix-prv.h b/stix/lib/stix-prv.h
index 754a8ab..29dc29f 100644
--- a/stix/lib/stix-prv.h
+++ b/stix/lib/stix-prv.h
@@ -140,10 +140,10 @@ typedef enum stix_iocmd_t stix_iocmd_t;
 typedef struct stix_iolxc_t stix_iolxc_t;
 struct stix_iolxc_t
 {
-	stix_char_t        c;    /**< character */
-	unsigned long      line; /**< line */
-	unsigned long      colm; /**< column */
-	const stix_char_t* file; /**< file specified in #include */
+	stix_uch_t        c;    /**< character */
+	unsigned long     line; /**< line */
+	unsigned long     colm; /**< column */
+	const stix_uch_t* file; /**< file specified in #include */
 };
 
 enum stix_ioarg_flag_t
@@ -160,7 +160,7 @@ struct stix_ioarg_t
 	 * It is #STIX_NULL for the main stream and points to a non-NULL string
 	 * for an included stream.
 	 */
-	const stix_char_t* name;   
+	const stix_uch_t* name;   
 
 	/** 
 	 * [OUT] I/O handle set by a handler. 
@@ -173,7 +173,7 @@ struct stix_ioarg_t
 	/**
 	 * [OUT] place data here 
 	 */
-	stix_char_t buf[1024];
+	stix_uch_t buf[1024];
 
 	/**
 	 * [IN] points to the data of the includer. It is #STIX_NULL for the
@@ -195,7 +195,7 @@ struct stix_ioarg_t
 	/*-----------------------------------------------------------------*/
 };
 
-typedef stix_oow_t (*stix_ioimpl_t) (
+typedef stix_ssize_t (*stix_ioimpl_t) (
 	stix_t*       stix,
 	stix_iocmd_t  cmd,
 	stix_ioarg_t* arg
@@ -260,13 +260,13 @@ stix_oow_t stix_hashbytes (
 );
 
 stix_oow_t stix_hashchars (
-	const stix_char_t* ptr,
+	const stix_uch_t*  ptr,
 	stix_oow_t         len
 );
 
 int stix_equalchars (
-	const stix_char_t* str1,
-	const stix_char_t* str2,
+	const stix_uch_t*  str1,
+	const stix_uch_t*  str2,
 	stix_oow_t         len
 );
 
@@ -289,7 +289,7 @@ stix_oop_t stix_allocoopobj (
 
 stix_oop_t stix_alloccharobj (
 	stix_t*            stix,
-	const stix_char_t* ptr,
+	const stix_uch_t* ptr,
 	stix_oow_t         len
 );
 
@@ -310,13 +310,13 @@ stix_oop_t stix_allocuint16obj (
 /* ========================================================================= */
 stix_oop_t stix_makesymbol (
 	stix_t*            stix,
-	const stix_char_t* ptr,
+	const stix_uch_t*  ptr,
 	stix_oow_t         len
 );
 
 stix_oop_t stix_findsymbol (
 	stix_t*            stix,
-	const stix_char_t* ptr,
+	const stix_uch_t*  ptr,
 	stix_oow_t         len
 );
 
@@ -338,22 +338,21 @@ stix_oop_t stix_getatsysdic (
 /* utf8.c                                                                    */
 /* ========================================================================= */
 stix_size_t stix_uctoutf8 (
-	stix_char_t   uc,
-	stix_bchar_t* utf8,
+	stix_uch_t    uc,
+	stix_bch_t*   utf8,
 	stix_size_t   size
 );
 
 stix_size_t stix_utf8touc (
-	const stix_bchar_t* utf8,
-	stix_size_t         size,
-	stix_char_t*        uc
+	const stix_bch_t* utf8,
+	stix_size_t       size,
+	stix_uch_t*       uc
 );
 
-
 int stix_ucstoutf8 (
-	const stix_char_t*   ucs,
+	const stix_uch_t*    ucs,
 	stix_size_t*         ucslen,
-	stix_bchar_t*        bcs,
+	stix_bch_t*          bcs,
 	stix_size_t*         bcslen
 );
 
@@ -363,27 +362,46 @@ int stix_ucstoutf8 (
  * It never returns -2 if \a ucs is #STIX_NULL.
  *
  * \code
- *  const stix_bchar_t* bcs = "a multibyte string";
- *  stix_char_t ucs[100];
+ *  const stix_bch_t* bcs = "test string";
+ *  stix_uch_t ucs[100];
  *  qse_size_t ucslen = STIX_COUNTOF(buf), n;
- *  qse_size_t bcslen = strlen(bcs);
+ *  qse_size_t bcslen = 11;
  *  int n;
  *  n = qse_bcstoucs (bcs, &bcslen, ucs, &ucslen);
  *  if (n <= -1) { invalid/incomplenete sequence or buffer to small }
  * \endcode
  *
+ * For a null-terminated string, you can specify ~(stix_size_t)0 in
+ * \a bcslen. The destination buffer \a ucs also must be large enough to
+ * store a terminating null. Otherwise, -2 is returned.
+ * 
+ * The resulting \a ucslen can still be greater than 0 even if the return
+ * value is negative. The value indiates the number of characters converted
+ * before the error has occurred.
+ *
  * \return 0 on success.
  *         -1 if \a bcs contains an illegal character.
  *         -2 if the wide-character string buffer is too small.
  *         -3 if \a bcs is not a complete sequence.
  */
 int stix_utf8toucs (
-	const stix_bchar_t* bcs,
+	const stix_bch_t*   bcs,
 	stix_size_t*        bcslen,
-	stix_char_t*        ucs,
+	stix_uch_t*         ucs,
 	stix_size_t*        ucslen
 );
 
+
+/**
+ * The stix_ucslen() function returns the number of characters before 
+ * a terminating null.
+ */
+/*
+stix_size_t stix_ucslen (
+	const stix_uch_t* ucs
+);
+*/
+
 /* ========================================================================= */
 /* comp.c                                                                    */
 /* ========================================================================= */
diff --git a/stix/lib/stix.c b/stix/lib/stix.c
index 4c48bcb..e68d23d 100644
--- a/stix/lib/stix.c
+++ b/stix/lib/stix.c
@@ -155,12 +155,12 @@ stix_oow_t stix_hashbytes (const stix_uint8_t* ptr, stix_oow_t len)
 	return h;
 }
 
-stix_oow_t stix_hashchars (const stix_char_t* ptr, stix_oow_t len)
+stix_oow_t stix_hashchars (const stix_uch_t* ptr, stix_oow_t len)
 {
 	return stix_hashbytes ((const stix_uint8_t *)ptr, len * STIX_SIZEOF(*ptr));
 }
 
-int stix_equalchars (const stix_char_t* str1, const stix_char_t* str2, stix_oow_t len)
+int stix_equalchars (const stix_uch_t* str1, const stix_uch_t* str2, stix_oow_t len)
 {
 	stix_oow_t i;
 
diff --git a/stix/lib/stix.h b/stix/lib/stix.h
index 170f415..b118670 100644
--- a/stix/lib/stix.h
+++ b/stix/lib/stix.h
@@ -44,9 +44,26 @@ typedef unsigned short int stix_uint16_t;
 #endif
 typedef unsigned long int stix_uintptr_t;
 typedef unsigned long int stix_size_t;
+typedef long int          stix_ssize_t;
 
-typedef unsigned short int stix_char_t; /* TODO ... wchar_t??? */
-typedef char               stix_bchar_t;
+typedef unsigned short int stix_uch_t; /* TODO ... wchar_t??? */
+typedef char               stix_bch_t;
+
+
+struct stix_ucs_t
+{
+	stix_uch_t* ptr;
+	stix_size_t len;
+};
+
+struct stix_bcs_t
+{
+	stix_bch_t* ptr;
+	stix_size_t len;
+};
+
+typedef struct stix_ucs_t stix_ucs_t;
+typedef struct stix_bcs_t stix_bcs_t;
 
 /* =========================================================================
  * PRIMITIVE MACROS
@@ -185,15 +202,15 @@ struct stix_mmgr_t
 
 typedef struct stix_cmgr_t stix_cmgr_t;
 
-typedef stix_size_t (*stix_cmgr_bctoc_t) (
-	const stix_bchar_t* mb, 
+typedef stix_size_t (*stix_cmgr_bctouc_t) (
+	const stix_bch_t*   mb, 
 	stix_size_t         size,
-	stix_char_t*        wc
+	stix_uch_t*         wc
 );
 
-typedef stix_size_t (*stix_cmgr_ctobc_t) (
-	stix_char_t  wc,
-	stix_bchar_t* mb,
+typedef stix_size_t (*stix_cmgr_uctobc_t) (
+	stix_uch_t    wc,
+	stix_bch_t*   mb,
 	stix_size_t   size
 );
 
@@ -206,8 +223,8 @@ typedef stix_size_t (*stix_cmgr_ctobc_t) (
  */
 struct stix_cmgr_t
 {
-	stix_cmgr_bctoc_t bctoc;
-	stix_cmgr_ctobc_t ctobc;
+	stix_cmgr_bctouc_t bctouc;
+	stix_cmgr_uctobc_t uctobc;
 };
 
 /* =========================================================================
@@ -258,7 +275,8 @@ enum stix_errnum_t
 	STIX_ENOMEM,  /**< insufficient memory */
 	STIX_EINVAL,  /**< invalid parameter or data */
 	STIX_ENOENT,  /**< no matching entry */
-	STIX_EIOERR   /**< I/O error */
+	STIX_EIOERR,  /**< I/O error */
+	STIX_EECERR   /**< encoding conversion error */
 };
 typedef enum stix_errnum_t stix_errnum_t;
 
@@ -605,7 +623,7 @@ struct stix_obj_oop_t
 struct stix_obj_char_t
 {
 	STIX_OBJ_HEADER;
-	stix_char_t slot[1];
+	stix_uch_t slot[1];
 };
 
 struct stix_obj_uint8_t
@@ -832,7 +850,7 @@ STIX_EXPORT void stix_gc (
  */
 STIX_EXPORT int stix_findclass (
 	stix_t*            vm,
-	const stix_char_t* name,
+	const stix_uch_t* name,
 	stix_oop_t*        oop
 );
 
diff --git a/stix/lib/sym.c b/stix/lib/sym.c
index 70adc10..37c8037 100644
--- a/stix/lib/sym.c
+++ b/stix/lib/sym.c
@@ -57,7 +57,7 @@ static stix_oop_oop_t expand_bucket (stix_t* stix, stix_oop_oop_t old_bucket)
 	return new_bucket;
 }
 
-static stix_oop_t find_or_make_symbol (stix_t* stix, const stix_char_t* ptr, stix_oow_t len, int create)
+static stix_oop_t find_or_make_symbol (stix_t* stix, const stix_uch_t* ptr, stix_oow_t len, int create)
 {
 	stix_oow_t index, tally;
 	stix_oop_char_t symbol;
@@ -130,12 +130,12 @@ static stix_oop_t find_or_make_symbol (stix_t* stix, const stix_char_t* ptr, sti
 	return (stix_oop_t)symbol;
 }
 
-stix_oop_t stix_makesymbol (stix_t* stix, const stix_char_t* ptr, stix_oow_t len)
+stix_oop_t stix_makesymbol (stix_t* stix, const stix_uch_t* ptr, stix_oow_t len)
 {
 	return find_or_make_symbol (stix, ptr, len, 1);
 }
 
-stix_oop_t stix_findsymbol (stix_t* stix, const stix_char_t* ptr, stix_oow_t len)
+stix_oop_t stix_findsymbol (stix_t* stix, const stix_uch_t* ptr, stix_oow_t len)
 {
 	return find_or_make_symbol (stix, ptr, len, 0);
 }
diff --git a/stix/lib/utf8.c b/stix/lib/utf8.c
index 3e09a90..300a2ae 100644
--- a/stix/lib/utf8.c
+++ b/stix/lib/utf8.c
@@ -26,7 +26,7 @@
 
 #include "stix-prv.h"
 
-#define STIX_BCLEN_MAX 16
+#define STIX_BCLEN_MAX 6
 
 /*
  * from RFC 2279 UTF-8, a transformation format of ISO 10646
@@ -62,12 +62,12 @@ static __utf8_t utf8_table[] =
 	{0x04000000ul, 0x7FFFFFFFul, 0xFC, 0xFE, 0x01, 6}
 };
 
-static STIX_INLINE __utf8_t* get_utf8_slot (stix_char_t uc)
+static STIX_INLINE __utf8_t* get_utf8_slot (stix_uch_t uc)
 {
 	__utf8_t* cur, * end;
 
-	STIX_ASSERT (STIX_SIZEOF(stix_bchar_t) == 1);
-	STIX_ASSERT (STIX_SIZEOF(stix_char_t) >= 2);
+	STIX_ASSERT (STIX_SIZEOF(stix_bch_t) == 1);
+	STIX_ASSERT (STIX_SIZEOF(stix_uch_t) >= 2);
 
 	end = utf8_table + STIX_COUNTOF(utf8_table);
 	cur = utf8_table;
@@ -81,7 +81,7 @@ static STIX_INLINE __utf8_t* get_utf8_slot (stix_char_t uc)
 	return STIX_NULL; /* invalid character */
 }
 
-stix_size_t stix_uctoutf8 (stix_char_t uc, stix_bchar_t* utf8, stix_size_t size)
+stix_size_t stix_uctoutf8 (stix_uch_t uc, stix_bch_t* utf8, stix_size_t size)
 {
 	__utf8_t* cur = get_utf8_slot (uc);
 
@@ -108,14 +108,14 @@ stix_size_t stix_uctoutf8 (stix_char_t uc, stix_bchar_t* utf8, stix_size_t size)
 	return (stix_size_t)cur->length;
 }
 
-stix_size_t stix_utf8touc (const stix_bchar_t* utf8, stix_size_t size, stix_char_t* uc)
+stix_size_t stix_utf8touc (const stix_bch_t* utf8, stix_size_t size, stix_uch_t* uc)
 {
 	__utf8_t* cur, * end;
 
 	STIX_ASSERT (utf8 != STIX_NULL);
 	STIX_ASSERT (size > 0);
-	STIX_ASSERT (STIX_SIZEOF(stix_bchar_t) == 1);
-	STIX_ASSERT (STIX_SIZEOF(stix_char_t) >= 2);
+	STIX_ASSERT (STIX_SIZEOF(stix_bch_t) == 1);
+	STIX_ASSERT (STIX_SIZEOF(stix_uch_t) >= 2);
 
 	end = utf8_table + STIX_COUNTOF(utf8_table);
 	cur = utf8_table;
@@ -135,7 +135,7 @@ stix_size_t stix_utf8touc (const stix_bchar_t* utf8, stix_size_t size, stix_char
 
 				if (uc)
 				{
-					stix_char_t w;
+					stix_uch_t w;
 
 					w = utf8[0] & cur->fmask;
 					for (i = 1; i < cur->length; i++)
@@ -167,9 +167,9 @@ stix_size_t stix_utf8touc (const stix_bchar_t* utf8, stix_size_t size, stix_char
 			}
 
 			/* this return value can indicate both 
-			 *    the correct length (len >= cur->length) 
+			 *    the correct length (size >= cur->length) 
 			 * and 
-			 *    the incomplete seqeunce error (len < cur->length).
+			 *    the incomplete seqeunce error (size < cur->length).
 			 */
 			return (stix_size_t)cur->length;
 		}
@@ -179,28 +179,26 @@ stix_size_t stix_utf8touc (const stix_bchar_t* utf8, stix_size_t size, stix_char
 	return 0; /* error - invalid sequence */
 }
 
-stix_size_t stix_utf8len (const stix_bchar_t* utf8, stix_size_t size)
-{
-	return stix_utf8touc (utf8, size, STIX_NULL);
-}
-
 /* ----------------------------------------------------------------------- */
 
-static int bcsn_to_csn_with_cmgr (
-	const stix_bchar_t* bcs, stix_size_t* bcslen,
-	stix_char_t* cs, stix_size_t* cslen, stix_cmgr_t* cmgr, int all)
+static STIX_INLINE int bcsn_to_ucsn_with_cmgr (
+	const stix_bch_t* bcs, stix_size_t* bcslen,
+	stix_uch_t* ucs, stix_size_t* ucslen, stix_cmgr_t* cmgr, int all)
 {
-	const stix_bchar_t* p;
+	const stix_bch_t* p;
 	int ret = 0;
 	stix_size_t mlen;
 
-	if (cs)
+	if (ucs)
 	{
-		stix_char_t* q, * qend;
+		/* destination buffer is specified. 
+		 * copy the conversion result to the buffer */
+
+		stix_uch_t* q, * qend;
 
 		p = bcs;
-		q = cs;
-		qend = cs + *cslen;
+		q = ucs;
+		qend = ucs + *ucslen;
 		mlen = *bcslen;
 
 		while (mlen > 0)
@@ -214,7 +212,7 @@ static int bcsn_to_csn_with_cmgr (
 				break;
 			}
 
-			n = cmgr->bctoc (p, mlen, q);
+			n = cmgr->bctouc (p, mlen, q);
 			if (n == 0)
 			{
 				/* invalid sequence */
@@ -249,12 +247,18 @@ static int bcsn_to_csn_with_cmgr (
 			mlen -= n;
 		}
 
-		*cslen = q - cs;
+		*ucslen = q - ucs;
 		*bcslen = p - bcs;
 	}
 	else
 	{
-		stix_char_t w;
+		/* no destination buffer is specified. perform conversion
+		 * but don't copy the result. the caller can call this function
+		 * without a buffer to find the required buffer size, allocate
+		 * a buffer with the size and call this function again with 
+		 * the buffer. */
+
+		stix_uch_t w;
 		stix_size_t wlen = 0;
 
 		p = bcs;
@@ -264,7 +268,7 @@ static int bcsn_to_csn_with_cmgr (
 		{
 			stix_size_t n;
 
-			n = cmgr->bctoc (p, mlen, &w);
+			n = cmgr->bctouc (p, mlen, &w);
 			if (n == 0)
 			{
 				/* invalid sequence */
@@ -291,19 +295,42 @@ static int bcsn_to_csn_with_cmgr (
 			wlen += 1;
 		}
 
-		*cslen = wlen;
+		*ucslen = wlen;
 		*bcslen = p - bcs;
 	}
 
 	return ret;
 }
 
-static int csn_to_bcsn_with_cmgr (
-	const stix_char_t* cs, stix_size_t* cslen,
-	stix_bchar_t* bcs, stix_size_t* bcslen, stix_cmgr_t* cmgr)
+static STIX_INLINE int bcs_to_ucs_with_cmgr (
+	const stix_bch_t* bcs, stix_size_t* bcslen,
+	stix_uch_t* ucs, stix_size_t* ucslen, stix_cmgr_t* cmgr, int all)
 {
-	const stix_char_t* p = cs;
-	const stix_char_t* end = cs + *cslen;
+	const stix_bch_t* bp;
+	stix_size_t mlen, wlen;
+	int n;
+
+	for (bp = bcs; *bp != '\0'; bp++);
+
+	mlen = bp - bcs; wlen = *ucslen;
+	n = bcsn_to_ucsn_with_cmgr (bcs, &mlen, ucs, &wlen, cmgr, all);
+	if (ucs)
+	{
+		/* null-terminate the target buffer if it has room for it. */
+		if (wlen < *ucslen) ucs[wlen] = '\0';
+		else n = -2; /* buffer too small */
+	}
+	*bcslen = mlen; *ucslen = wlen;
+
+	return n;
+}
+
+static STIX_INLINE int ucsn_to_bcsn_with_cmgr (
+	const stix_uch_t* ucs, stix_size_t* ucslen,
+	stix_bch_t* bcs, stix_size_t* bcslen, stix_cmgr_t* cmgr)
+{
+	const stix_uch_t* p = ucs;
+	const stix_uch_t* end = ucs + *ucslen;
 	int ret = 0; 
 
 	if (bcs)
@@ -320,7 +347,7 @@ static int csn_to_bcsn_with_cmgr (
 				break;
 			}
 
-			n = cmgr->ctobc (*p, bcs, rem);
+			n = cmgr->uctobc (*p, bcs, rem);
 			if (n == 0) 
 			{
 				ret = -1;
@@ -338,14 +365,96 @@ static int csn_to_bcsn_with_cmgr (
 	}
 	else
 	{
-		stix_bchar_t bcsbuf[STIX_BCLEN_MAX];
+		stix_bch_t bcsbuf[STIX_BCLEN_MAX];
 		stix_size_t mlen = 0;
 
 		while (p < end)
 		{
 			stix_size_t n;
 
-			n = cmgr->ctobc (*p, bcsbuf, STIX_COUNTOF(bcsbuf));
+			n = cmgr->uctobc (*p, bcsbuf, STIX_COUNTOF(bcsbuf));
+			if (n == 0) 
+			{
+				ret = -1;
+				break; /* illegal character */
+			}
+
+			/* it assumes that bcsbuf is large enough to hold a character */
+			STIX_ASSERT (n <= STIX_COUNTOF(bcsbuf));
+
+			p++; mlen += n;
+		}
+
+		/* this length excludes the terminating null character. 
+		 * this function doesn't even null-terminate the result. */
+		*bcslen = mlen;
+	}
+
+	*ucslen = p - ucs;
+	return ret;
+}
+
+
+static int ucs_to_bcs_with_cmgr (
+	const stix_uch_t* ucs, stix_size_t* ucslen,
+	stix_bch_t* bcs, stix_size_t* bcslen, stix_cmgr_t* cmgr)
+{
+	const stix_uch_t* p = ucs;
+	int ret = 0;
+
+	if (bcs)
+	{
+		stix_size_t rem = *bcslen;
+
+		while (*p != '\0')
+		{
+			stix_size_t n;
+
+			if (rem <= 0)
+			{
+				ret = -2;
+				break;
+			}
+			
+			n = cmgr->uctobc (*p, bcs, rem);
+			if (n == 0) 
+			{
+				ret = -1;
+				break; /* illegal character */
+			}
+			if (n > rem) 
+			{
+				ret = -2;
+				break; /* buffer too small */
+			}
+
+			bcs += n; rem -= n; p++;
+		}
+
+		/* update bcslen to the length of the bcs string converted excluding
+		 * terminating null */
+		*bcslen -= rem; 
+
+		/* null-terminate the multibyte sequence if it has sufficient space */
+		if (rem > 0) *bcs = '\0';
+		else 
+		{
+			/* if ret is -2 and cs[cslen] == '\0', 
+			 * this means that the bcs buffer was lacking one
+			 * slot for the terminating null */
+			ret = -2; /* buffer too small */
+		}
+	}
+	else
+	{
+		stix_bch_t bcsbuf[STIX_BCLEN_MAX];
+		stix_size_t mlen = 0;
+
+		while (*p != '\0')
+		{
+			stix_size_t n;
+
+			n = cmgr->uctobc (*p, bcsbuf, STIX_COUNTOF(bcsbuf));
 			if (n == 0) 
 			{
 				ret = -1;
@@ -353,22 +462,20 @@ static int csn_to_bcsn_with_cmgr (
 			}
 
 			/* it assumes that bcs is large enough to hold a character */
-			STIX_ASSERT (n <= STIX_COUNTOF(bcsbuf));
+			STIX_ASSERT (n <= STIX_COUNTOF(bcs));
 
 			p++; mlen += n;
 		}
 
-		/* this length excludes the terminating null character. 
-		 * this function doesn't event null-terminate the result. */
+		/* this length holds the number of resulting multi-byte characters 
+		 * excluding the terminating null character */
 		*bcslen = mlen;
 	}
 
-	*cslen = p - cs;
-
+	*ucslen = p - ucs;  /* the number of wide characters handled. */
 	return ret;
 }
 
-
 static stix_cmgr_t utf8_cmgr =
 {
 	stix_utf8touc,
@@ -376,15 +483,42 @@ static stix_cmgr_t utf8_cmgr =
 };
 
 int stix_utf8toucs (
-	const stix_bchar_t* bcs, stix_size_t* bcslen,
-	stix_char_t* ucs, stix_size_t* ucslen)
+	const stix_bch_t* bcs, stix_size_t* bcslen,
+	stix_uch_t* ucs, stix_size_t* ucslen)
 {
-	return bcsn_to_csn_with_cmgr (bcs, bcslen, ucs, ucslen, &utf8_cmgr, 0);
+	if (*bcslen == ~(stix_size_t)0)
+	{
+		/* the source is null-terminated. */
+		return bcs_to_ucs_with_cmgr (bcs, bcslen, ucs, ucslen, &utf8_cmgr, 0);
+	}
+	else
+	{
+		/* the source is length bound */
+		return bcsn_to_ucsn_with_cmgr (bcs, bcslen, ucs, ucslen, &utf8_cmgr, 0);
+	}
 }
 
 int stix_ucstoutf8 (
-	const stix_char_t* ucs, stix_size_t *ucslen,
-	stix_bchar_t* bcs, stix_size_t* bcslen)
+	const stix_uch_t* ucs, stix_size_t *ucslen,
+	stix_bch_t* bcs, stix_size_t* bcslen)
 {
-	return csn_to_bcsn_with_cmgr (ucs, ucslen, bcs, bcslen, &utf8_cmgr);
+	if (*ucslen == ~(stix_size_t)0)
+	{
+		/* null-terminated */
+		return ucs_to_bcs_with_cmgr (ucs, ucslen, bcs, bcslen, &utf8_cmgr);
+	}
+	else
+	{
+		/* length bound */
+		return ucsn_to_bcsn_with_cmgr (ucs, ucslen, bcs, bcslen, &utf8_cmgr);
+	}
 }
+
+/*
+stix_size_t stix_ucslen (const stix_uch_t* ucs)
+{
+	const stix_uch_t* ptr = ucs;
+	while  (*ptr) ptr = STIX_INCPTR(const stix_uch_t, ptr, 1);
+	return STIX_SUBPTR(const stix_uch_t, ptr, ucs);
+}
+*/