diff --git a/stix/kernel/Stdio.st b/stix/kernel/Stdio.st
index 6feebdf..04d408e 100644
--- a/stix/kernel/Stdio.st
+++ b/stix/kernel/Stdio.st
@@ -1,9 +1,9 @@
 #class(#byte) Stdio(Object) from 'stdio'
 {
-	#method(#class) _newInstSize
-	{
-		<primitive: #stdio_newInstSize>
-	}
+##	#method(#class) _newInstSize
+##	{
+##		<primitive: #stdio._newInstSize>
+##	}
 
 	#method(#class) new: size
 	{
@@ -26,12 +26,12 @@
 
 ##	#method open: name for: mode
 ##	{
-##		<primitive: #stdio_open>
+##		<primitive: #stdio.open>
 ##	}
 
 ##	#method close
 ##	{
-##		<primitive: #stdio_close>
+##		<primitive: #stdio.close>
 ##	}
 }
 
diff --git a/stix/lib/comp.c b/stix/lib/comp.c
index ee71c34..8f64a7c 100644
--- a/stix/lib/comp.c
+++ b/stix/lib/comp.c
@@ -2703,7 +2703,9 @@ static int compile_method_primitive (stix_t* stix)
 {
 	/* 
 	 * method-primitive := "<"  "primitive:" integer ">" |
-	 *                     "<"  "exception" ">"
+	 *                     "<"  "primitive:" symbol ">" |
+	 *                     "<"  "exception" ">" |
+	 *                     "<"  "ensure" ">"
 	 */
 	stix_ooi_t pfnum;
 	const stix_ooch_t* ptr, * end;
@@ -2752,8 +2754,10 @@ static int compile_method_primitive (stix_t* stix)
 				pfnum = stix_getpfnum (stix, tptr, tlen);
 				if (pfnum <= -1)
 				{
+					/* a built-in primitive function is not found 
+					 * check if it is a primitive function identifier */
+#if 0
 					const stix_ooch_t* us;
-					/* the primitive function is not found */
 					us = stix_findoochar (tptr, tlen, '_');
 					if (us > tptr && us < tptr + tlen - 1)
 					{
@@ -2768,6 +2772,18 @@ static int compile_method_primitive (stix_t* stix)
 							break;
 						}
 					}
+#else
+					stix_oow_t lit_idx;
+
+					if (add_symbol_literal(stix, TOKEN_NAME(stix), 1, &lit_idx) >= 0 &&
+					    STIX_OOI_IN_METHOD_PREAMBLE_INDEX_RANGE(lit_idx))
+					{
+						stix->c->mth.pftype = 2; /* named primitive */
+						stix->c->mth.pfnum = lit_idx;
+						break;
+					}
+
+#endif
 
 					/* wrong primitive number */
 					set_syntax_error (stix, STIX_SYNERR_PFID, TOKEN_LOC(stix), TOKEN_NAME(stix));
diff --git a/stix/lib/exec.c b/stix/lib/exec.c
index df54abf..5cd908a 100644
--- a/stix/lib/exec.c
+++ b/stix/lib/exec.c
@@ -2745,7 +2745,7 @@ int stix_getpfnum (stix_t* stix, const stix_ooch_t* ptr, stix_oow_t len)
 
 	for (i = 0; i < STIX_COUNTOF(pftab); i++)
 	{
-		if (stix_compucxbcstr(ptr, len, pftab[i].name) == 0)
+		if (stix_compucharsbcstr(ptr, len, pftab[i].name) == 0)
 		{
 			return i;
 		}
diff --git a/stix/lib/stix-utl.h b/stix/lib/stix-utl.h
index 92d4018..5aeae88 100644
--- a/stix/lib/stix-utl.h
+++ b/stix/lib/stix-utl.h
@@ -39,9 +39,10 @@ extern "C" {
 #	define stix_compoocbcstr(str1,str2) stix_compucbcstr(str1,str2)
 #	define stix_compoocstr(str1,str2) stix_compucstr(str1,str2)
 #	define stix_copyoochars(dst,src,len) stix_copyuchars(dst,src,len)
-#	define stix_copybchtooochars(dst,src,len) stix_copybchtouchars(dst,src,len)
+#	define stix_copybctooochars(dst,src,len) stix_copybctouchars(dst,src,len)
 #	define stix_copyoocstr(dst,len,src) stix_copyucstr(dst,len,src)
 #	define stix_findoochar(ptr,len,c) stix_finduchar(ptr,len,c)
+#	define stix_rfindoochar(ptr,len,c) stix_rfinduchar(ptr,len,c)
 #	define stix_countoocstr(str) stix_countucstr(str)
 #else
 #	define stix_hashchars(ptr,len) stix_hashbchars(ptr,len)
@@ -49,9 +50,10 @@ extern "C" {
 #	define stix_compoocbcstr(str1,str2) stix_compbcstr(str1,str2)
 #	define stix_compoocstr(str1,str2) stix_compbcstr(str1,str2)
 #	define stix_copyoochars(dst,src,len) stix_copybchars(dst,src,len)
-#	define stix_copybchtooochars(dst,src,len) stix_copybchars(dst,src,len)
+#	define stix_copybctooochars(dst,src,len) stix_copybchars(dst,src,len)
 #	define stix_copyoocstr(dst,len,src) stix_copybcstr(dst,len,src)
 #	define stix_findoochar(ptr,len,c) stix_findbchar(ptr,len,c)
+#	define stix_rfindoochar(ptr,len,c) stix_rfindbchar(ptr,len,c)
 #	define stix_countoocstr(str) stix_countbcstr(str)
 #endif
 
@@ -102,7 +104,7 @@ STIX_EXPORT int stix_compucbcstr (
 	const stix_bch_t* str2
 );
 
-STIX_EXPORT int stix_compucxbcstr (
+STIX_EXPORT int stix_compucharsbcstr (
 	const stix_uch_t* str1,
 	stix_oow_t        len,
 	const stix_bch_t* str2
@@ -120,7 +122,7 @@ STIX_EXPORT void stix_copybchars (
 	stix_oow_t        len
 );
 
-STIX_EXPORT void stix_copybchtouchars (
+STIX_EXPORT void stix_copybctouchars (
 	stix_uch_t*       dst,
 	const stix_bch_t* src,
 	stix_oow_t        len
@@ -150,6 +152,19 @@ STIX_EXPORT stix_bch_t* stix_findbchar (
 	stix_bch_t        c
 );
 
+STIX_EXPORT stix_uch_t* stix_rfinduchar (
+	const stix_uch_t* ptr,
+	stix_oow_t        len,
+	stix_uch_t        c
+);
+
+STIX_EXPORT stix_bch_t* stix_rfindbchar (
+	const stix_bch_t* ptr,
+	stix_oow_t        len,
+	stix_bch_t        c
+);
+
+
 STIX_EXPORT stix_oow_t stix_countucstr (
 	const stix_uch_t* str
 );
@@ -158,6 +173,18 @@ STIX_EXPORT stix_oow_t stix_countbcstr (
 	const stix_bch_t* str
 );
 
+STIX_EXPORT int stix_copyoocstrtosbuf (
+	stix_t*            stix,
+	const stix_ooch_t* str,
+	int                id
+);
+
+STIX_EXPORT int stix_concatoocstrtosbuf (
+	stix_t*            stix,
+	const stix_ooch_t* str,
+	int                id
+);
+
 STIX_EXPORT stix_cmgr_t* stix_getutf8cmgr (
 	void
 );
diff --git a/stix/lib/stix.c b/stix/lib/stix.c
index ea65936..8af5dc3 100644
--- a/stix/lib/stix.c
+++ b/stix/lib/stix.c
@@ -137,6 +137,7 @@ static stix_rbt_walk_t unload_module (stix_rbt_t* rbt, stix_rbt_pair_t* pair, vo
 void stix_fini (stix_t* stix)
 {
 	stix_cb_t* cb;
+	stix_oow_t i;
 
 	if (stix->sem_list)
 	{
@@ -176,6 +177,17 @@ void stix_fini (stix_t* stix)
 	/* deregister all callbacks */
 	while (stix->cblist) stix_deregcb (stix, stix->cblist);
 
+	for (i = 0; i < STIX_COUNTOF(stix->sbuf); i++)
+	{
+		if (stix->sbuf[i].ptr)
+		{
+			stix_freemem (stix, stix->sbuf[i].ptr);
+			stix->sbuf[i].ptr = STIX_NULL;
+			stix->sbuf[i].len = 0;
+			stix->sbuf[i].capa = 0;
+		}
+	}
+
 	if (stix->log.ptr) 
 	{
 		/* make sure to flush your log message */
@@ -442,7 +454,7 @@ stix_mod_data_t* stix_openmod (stix_t* stix, const stix_ooch_t* name, stix_oow_t
 	stix_ooch_t buf[MOD_PREFIX_LEN + STIX_MOD_NAME_LEN_MAX + 1 + 1]; 
 
 	/* the terminating null isn't needed in buf here */
-	stix_copybchtooochars (buf, MOD_PREFIX, MOD_PREFIX_LEN); 
+	stix_copybctooochars (buf, MOD_PREFIX, MOD_PREFIX_LEN); 
 
 	if (namelen > STIX_COUNTOF(buf) - (MOD_PREFIX_LEN + 1 + 1))
 	{
@@ -643,14 +655,14 @@ stix_pfimpl_t stix_querymod (stix_t* stix, const stix_ooch_t* pfid, stix_oow_t p
 	stix_oow_t mod_name_len;
 	stix_pfimpl_t handler;
 
-	sep = stix_findoochar (pfid, pfidlen, '_');
+	sep = stix_findoochar (pfid, pfidlen, '.');
 	if (!sep)
 	{
 		/* i'm writing a conservative code here. the compiler should 
 		 * guarantee that an underscore is included in an primitive identifer.
 		 * what if the compiler is broken? imagine a buggy compiler rewritten
 		 * in stix itself? */
-		STIX_DEBUG2 (stix, "Internal error - no underscore in a primitive function identifier [%.*S] - buggy compiler?\n", pfidlen, pfid);
+		STIX_DEBUG2 (stix, "Internal error - no period in a primitive function identifier [%.*S] - buggy compiler?\n", pfidlen, pfid);
 		stix->errnum = STIX_EINTERN;
 		return STIX_NULL;
 	}
@@ -694,9 +706,12 @@ int stix_genpfmethod (stix_t* stix, stix_mod_t* mod, stix_oop_t _class, stix_met
 	stix_oow_t tmp_count = 0, i;
 	stix_ooi_t arg_count = 0;
 	stix_oocs_t cs;
+	static stix_ooch_t dot[] = { '.', '\0' };
 
 	STIX_ASSERT (STIX_CLASSOF(stix, _class) == stix->_class);
 
+	if (!pfname) pfname = mthname;
+
 	cls = (stix_oop_class_t)_class;
 	stix_pushtmp (stix, (stix_oop_t*)&cls); tmp_count++;
 	STIX_ASSERT (STIX_CLASSOF(stix, (stix_oop_t)cls->mthdic[type]) == stix->_method_dictionary);
@@ -727,10 +742,22 @@ int stix_genpfmethod (stix_t* stix, stix_mod_t* mod, stix_oop_t _class, stix_met
 	if (!mnsym) goto oops;
 	stix_pushtmp (stix, (stix_oop_t*)&mnsym); tmp_count++;
 
-/* TODO:... */
-/* pfid => mod->name + '_' + pfname */
-	pfidsym = (stix_oop_char_t)stix_makesymbol (stix, pfname, stix_countoocstr(pfname));
-	if (!pfidsym) goto oops;
+	/* compose a full primitive function identifier to VM's string buffer.
+	 *   pfid => mod->name + '.' + pfname */
+	if (stix_copyoocstrtosbuf(stix, mod->name, 0) <= -1 ||
+	    stix_concatoocstrtosbuf(stix, dot, 0) <= -1 ||
+	    stix_concatoocstrtosbuf(stix, pfname, 0) <=  -1) 
+	{
+		STIX_DEBUG2 (stix, "Cannot generate primitive function method [%S] in [%O] - VM memory shortage\n", mthname, cls->name);
+		return -1;
+	}
+
+	pfidsym = (stix_oop_char_t)stix_makesymbol (stix, stix->sbuf[0].ptr, stix->sbuf[0].len);
+	if (!pfidsym) 
+	{
+		STIX_DEBUG2 (stix, "Cannot generate primitive function method [%S] in [%O] - symbol instantiation failure\n", mthname, cls->name);
+		goto oops;
+	}
 	stix_pushtmp (stix, (stix_oop_t*)&pfidsym); tmp_count++;
 
 #if defined(STIX_USE_OBJECT_TRAILER)
@@ -738,12 +765,16 @@ int stix_genpfmethod (stix_t* stix, stix_mod_t* mod, stix_oop_t _class, stix_met
 #else
 	mth = (stix_oop_method_t)stix_instantiate (stix, stix->_method, STIX_NULL, 1);
 #endif
-	if (!mth) goto oops;
+	if (!mth)
+	{
+		STIX_DEBUG2 (stix, "Cannot generate primitive function method [%S] in [%O] - method instantiation failure\n", mthname, cls->name);
+		goto oops;
+	}
 
 	/* store the primitive function name symbol to the literal frame */
 	mth->slot[0] = (stix_oop_t)pfidsym;
 
-	/* premable should contain the index to the literal frame - 0 */
+	/* premable should contain the index to the literal frame which is always 0 */
 	mth->owner = cls;
 	mth->name = mnsym;
 	mth->preamble = STIX_SMOOI_TO_OOP(STIX_METHOD_MAKE_PREAMBLE(STIX_METHOD_PREAMBLE_NAMED_PRIMITIVE, 0));
@@ -751,12 +782,20 @@ int stix_genpfmethod (stix_t* stix, stix_mod_t* mod, stix_oop_t _class, stix_met
 	mth->preamble_data[1] = STIX_SMOOI_TO_OOP(0);
 	mth->tmpr_count = STIX_SMOOI_TO_OOP(arg_count);
 	mth->tmpr_nargs = STIX_SMOOI_TO_OOP(arg_count);
-	stix_poptmps (stix, tmp_count); tmp_count = 0;
+
+	
 
 /* TODO: emit BCODE_RETURN_NIL ? */
 
-	if (!stix_putatdic (stix, cls->mthdic[type], (stix_oop_t)mnsym, (stix_oop_t)mth)) goto oops;
+	if (!stix_putatdic (stix, cls->mthdic[type], (stix_oop_t)mnsym, (stix_oop_t)mth)) 
+	{
+		STIX_DEBUG2 (stix, "Cannot generate primitive function method [%S] in [%O] - failed to add to method dictionary\n", mthname, cls->name);
+		goto oops;
+	}
 
+	STIX_DEBUG2 (stix, "Generated primitive function method [%S] in [%O]\n", mthname, cls->name);
+
+	stix_poptmps (stix, tmp_count); tmp_count = 0;
 	return 0;
 
 oops:
diff --git a/stix/lib/stix.h b/stix/lib/stix.h
index 4570161..cbbb1f7 100644
--- a/stix/lib/stix.h
+++ b/stix/lib/stix.h
@@ -782,6 +782,14 @@ struct stix_mod_data_t
 };
 typedef struct stix_mod_data_t stix_mod_data_t;
 
+struct stix_sbuf_t
+{
+	stix_ooch_t* ptr;
+	stix_oow_t len;
+	stix_oow_t capa;
+};
+typedef struct stix_sbuf_t stix_sbuf_t;
+
 /* =========================================================================
  * STIX VM
  * ========================================================================= */
@@ -912,6 +920,8 @@ struct stix_t
 	} rsrc;
 	/* == END RSRC MANAGEMENT == */
 
+	stix_sbuf_t sbuf[64];
+
 #if defined(STIX_INCLUDE_COMPILER)
 	stix_compiler_t* c;
 #endif
diff --git a/stix/lib/sym.c b/stix/lib/sym.c
index 1b47cfa..5d329f2 100644
--- a/stix/lib/sym.c
+++ b/stix/lib/sym.c
@@ -175,7 +175,6 @@ stix_oop_t stix_makesymbol (stix_t* stix, const stix_ooch_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_ooch_t* ptr, stix_oow_t len)
 {
 	return find_or_make_symbol (stix, ptr, len, 0);
diff --git a/stix/lib/utl.c b/stix/lib/utl.c
index d60fd2a..df6cc60 100644
--- a/stix/lib/utl.c
+++ b/stix/lib/utl.c
@@ -28,6 +28,12 @@
 
 #define STIX_BCLEN_MAX 6
 
+/* some naming conventions
+ *  bchars, uchars -> pointer and length
+ *  bcstr, ucstr -> null-terminated string pointer
+ *  bctouchars -> bchars to uchars
+ */
+
 stix_oow_t stix_hashbytes (const stix_oob_t* ptr, stix_oow_t len)
 {
 	stix_oow_t h = 0;
@@ -101,7 +107,7 @@ int stix_compucbcstr (const stix_uch_t* str1, const stix_bch_t* str2)
 	return (*str1 > *str2)? 1: -1;
 }
 
-int stix_compucxbcstr (const stix_uch_t* str1, stix_oow_t len, const stix_bch_t* str2)
+int stix_compucharsbcstr (const stix_uch_t* str1, stix_oow_t len, const stix_bch_t* str2)
 {
 	const stix_uch_t* end = str1 + len;
 	while (str1 < end && *str2 != '\0' && *str1 == *str2) str1++, str2++;
@@ -122,7 +128,7 @@ void stix_copybchars (stix_bch_t* dst, const stix_bch_t* src, stix_oow_t len)
 	for (i = 0; i < len; i++) dst[i] = src[i];
 }
 
-void stix_copybchtouchars (stix_uch_t* dst, const stix_bch_t* src, stix_oow_t len)
+void stix_copybctouchars (stix_uch_t* dst, const stix_bch_t* src, stix_oow_t len)
 {
 	stix_oow_t i;
 	for (i = 0; i < len; i++) dst[i] = src[i];
@@ -202,6 +208,73 @@ stix_bch_t* stix_findbchar (const stix_bch_t* ptr, stix_oow_t len, stix_bch_t c)
 	return STIX_NULL;
 }
 
+stix_uch_t* stix_rfinduchar (const stix_uch_t* ptr, stix_oow_t len, stix_uch_t c)
+{
+	const stix_uch_t* cur;
+
+	cur = ptr + len;
+	while (cur > ptr)
+	{
+		--cur;
+		if (*cur == c) return (stix_uch_t*)cur;
+	}
+
+	return STIX_NULL;
+}
+
+stix_bch_t* stix_rfindbchar (const stix_bch_t* ptr, stix_oow_t len, stix_bch_t c)
+{
+	const stix_bch_t* cur;
+
+	cur = ptr + len;
+	while (cur > ptr)
+	{
+		--cur;
+		if (*cur == c) return (stix_bch_t*)cur;
+	}
+
+	return STIX_NULL;
+}
+
+/* ----------------------------------------------------------------------- */
+
+int stix_concatoocstrtosbuf (stix_t* stix, const stix_ooch_t* str, int id)
+{
+	stix_sbuf_t* p;
+	stix_oow_t len;
+
+	p = &stix->sbuf[id];
+	len = stix_countoocstr (str);
+
+	if (len > p->capa - p->len)
+	{
+		stix_oow_t newcapa;
+		stix_ooch_t* tmp;
+
+		newcapa = STIX_ALIGN(p->len + len, 512); /* TODO: adjust this capacity */
+
+		/* +1 to handle line ending injection more easily */
+		tmp = stix_reallocmem (stix, p->ptr, (newcapa + 1) * STIX_SIZEOF(*tmp)); 
+		if (!tmp) return -1;
+
+		p->ptr = tmp;
+		p->capa = newcapa;
+	}
+
+	stix_copyoochars (&p->ptr[p->len], str, len);
+	p->len += len;
+	p->ptr[p->len] = '\0';
+
+	return 0;
+}
+
+int stix_copyoocstrtosbuf (stix_t* stix, const stix_ooch_t* str, int id)
+{
+	stix->sbuf[id].len = 0;;
+	return stix_concatoocstrtosbuf (stix, str, id);
+}
+
+
 
 /* ----------------------------------------------------------------------- */
 
diff --git a/stix/mod/stdio.c b/stix/mod/stdio.c
index 56b6a1e..82d2105 100644
--- a/stix/mod/stdio.c
+++ b/stix/mod/stdio.c
@@ -116,29 +116,33 @@ static int pf_newinstsize (stix_t* stix, stix_ooi_t nargs)
 typedef struct fnctab_t fnctab_t;
 struct fnctab_t
 {
-	const stix_bch_t* name;
+	const stix_bch_t* mthname;
+	const stix_bch_t* pfname;
 	stix_pfimpl_t handler;
 };
 
 static fnctab_t fnctab[] =
 {
-	{ "close",       pf_close         },
-	{ "newInstSize", pf_newinstsize   },
-	{ "open",        pf_open          },
-	{ "puts",        pf_puts          }
+	{ "_newInstSize", STIX_NULL, pf_newinstsize   },
+	{ "close",        STIX_NULL, pf_close         },
+	{ "open:for:",    STIX_NULL, pf_open          },
+	{ "puts",         STIX_NULL, pf_puts          }
 };
 
 
 static stix_ooch_t voca_open_for[] = { 'o','p','e','n',':','f','o','r',':','\0' };
 static stix_ooch_t voca_open[] = { 'o','p','e','n','\0' };
 static stix_ooch_t voca_close[] = { 'c','l','o','s','e','\0' };
+static stix_ooch_t voca_newInstSize[] = { '_','n','e','w','I','n','s','t','S','i','z','e','\0' };
+
 /* ------------------------------------------------------------------------ */
 
 static int import (stix_t* stix, stix_mod_t* mod, stix_oop_t _class)
 {
 stix_pushtmp (stix, &_class);
-	stix_genpfmethod (stix, mod, _class, STIX_METHOD_INSTANCE, voca_open_for, voca_open);
-	stix_genpfmethod (stix, mod, _class, STIX_METHOD_CLASS, voca_close, voca_close);
+	stix_genpfmethod (stix, mod, _class, STIX_METHOD_CLASS, voca_newInstSize, STIX_NULL);
+	stix_genpfmethod (stix, mod, _class, STIX_METHOD_INSTANCE, voca_open_for, STIX_NULL);
+	stix_genpfmethod (stix, mod, _class, STIX_METHOD_INSTANCE, voca_close, voca_close);
 stix_poptmp (stix);
 	return 0;
 }
@@ -153,7 +157,7 @@ static stix_pfimpl_t query (stix_t* stix, stix_mod_t* mod, const stix_ooch_t* na
 	{
 		mid = (left + right) / 2;
 
-		n = stix_compoocbcstr (name, fnctab[mid].name);
+		n = stix_compoocbcstr (name, fnctab[mid].mthname);
 		if (n < 0) right = mid - 1; 
 		else if (n > 0) left = mid + 1;
 		else