diff --git a/100_core/src/gplx/Array_.java b/100_core/src/gplx/Array_.java
index 3efe7d815..cb0771c15 100644
--- a/100_core/src/gplx/Array_.java
+++ b/100_core/src/gplx/Array_.java
@@ -54,6 +54,15 @@ public class Array_ {
 		Copy_to(src, 0, trg, 0, copy_len);
 		return trg;
 	}
+	public static Object Extract_by_pos(Object src, int src_bgn) { 
+		return Extract_by_pos(src, src_bgn, Array.getLength(src)); 
+	}
+	public static Object Extract_by_pos(Object src, int src_bgn, int src_end) { 
+		int trg_len = src_end - src_bgn;
+		Object trg = Create(Component_type(src), trg_len);       
+		Copy_to(src, src_bgn, trg, 0, src_end - src_bgn);
+		return trg;
+	}
 	public static List_adp To_list(Object ary) {	
 		int aryLen = Array_.Len(ary);
 		List_adp rv = List_adp_.New();
diff --git a/100_core/src/gplx/Keyval_.java b/100_core/src/gplx/Keyval_.java
index 8fb562139..970fe6409 100644
--- a/100_core/src/gplx/Keyval_.java
+++ b/100_core/src/gplx/Keyval_.java
@@ -70,6 +70,14 @@ public class Keyval_ {
 		Ary__to_str__nest__ary(bfr, 0, true, ary);
 		return bfr.To_str_and_clear();
 	}
+	public static Object[] Ary__to_objary__val(Keyval[] ary) {
+		int ary_len = ary.length;
+		Object[] rv = new Object[ary_len];
+		for (int i = 0; i < ary_len; i++) {
+			rv[i] = ary[i].Val();
+		}
+		return rv;
+	}
 	private static void Ary__to_str__nest__ary(Bry_bfr bfr, int indent, boolean is_kv, Object[] ary) {
 		int len = ary.length;
 		for (int i = 0; i < len; ++i) {
diff --git a/100_core/src/gplx/core/tests/Gftest.java b/100_core/src/gplx/core/tests/Gftest.java
index 44f583d72..31dc41d1a 100644
--- a/100_core/src/gplx/core/tests/Gftest.java
+++ b/100_core/src/gplx/core/tests/Gftest.java
@@ -17,6 +17,7 @@ package gplx.core.tests; import gplx.*; import gplx.core.*;
 import gplx.core.brys.*;
 public class Gftest {
 	private static final    Bry_bfr bfr = Bry_bfr_.New();
+	public static void Eq__ary(Object[] expd, Object[] actl, String msg_fmt, Object... msg_args)      {Eq__array(Type_ids_.Id__obj, expd, actl, msg_fmt, msg_args);}
 	public static void Eq__ary(boolean[] expd, boolean[] actl, String msg_fmt, Object... msg_args)			{Eq__array(Type_ids_.Id__bool, expd, actl, msg_fmt, msg_args);}
 	public static void Eq__ary(int[] expd, int[] actl, String msg_fmt, Object... msg_args)			{Eq__array(Type_ids_.Id__int, expd, actl, msg_fmt, msg_args);}
 	public static void Eq__ary(long[] expd, long[] actl, String msg_fmt, Object... msg_args)			{Eq__array(Type_ids_.Id__long, expd, actl, msg_fmt, msg_args);}
@@ -151,12 +152,14 @@ public class Gftest {
 	}
 	private static void Write__itm(Bry_bfr bfr, int type_id, Object ary, int len, int idx) {
 		if (idx < len) {
+			Object val = Array_.Get_at(ary, idx);
 			switch (type_id) {
-				case Type_ids_.Id__bool:	bfr.Add_yn(Bool_.Cast(Array_.Get_at(ary, idx))); break;
-				case Type_ids_.Id__bry:		bfr.Add_safe((byte[])Array_.Get_at(ary, idx)); break;
-				case Type_ids_.Id__long:	bfr.Add_long_variable(Long_.cast(Array_.Get_at(ary, idx))); break;
-				case Type_ids_.Id__int:		bfr.Add_int_variable(Int_.Cast(Array_.Get_at(ary, idx))); break;
-				case Type_ids_.Id__byte:	bfr.Add_int_variable((int)(Byte_.Cast(Array_.Get_at(ary, idx)))); break;
+				case Type_ids_.Id__bool:	bfr.Add_yn(Bool_.Cast(val)); break;
+				case Type_ids_.Id__bry:		bfr.Add_safe((byte[])val); break;
+				case Type_ids_.Id__long:	bfr.Add_long_variable(Long_.cast(val)); break;
+				case Type_ids_.Id__int:		bfr.Add_int_variable(Int_.Cast(val)); break;
+				case Type_ids_.Id__byte:	bfr.Add_int_variable((int)(Byte_.Cast(val))); break;
+				case Type_ids_.Id__obj:     bfr.Add_str_u8(Object_.Xto_str_strict_or_null_mark(val)); break;
 				default:					throw Err_.new_unhandled_default(type_id);
 			}
 		}
@@ -182,6 +185,7 @@ public class Gftest {
 					case Type_ids_.Id__long:		eq = Long_.cast(expd_obj) == Long_.cast(actl_obj); break;
 					case Type_ids_.Id__int:			eq = Int_.Cast(expd_obj) == Int_.Cast(actl_obj); break;
 					case Type_ids_.Id__byte:		eq = Byte_.Cast(expd_obj) == Byte_.Cast(actl_obj); break;
+					case Type_ids_.Id__obj:         eq = Object_.Eq(expd_obj, actl_obj); break;
 				}
 			}
 			if (!eq) {
diff --git a/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring.java b/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring.java
index dd7eb67b3..5ecaea81e 100644
--- a/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring.java
+++ b/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring.java
@@ -14,7 +14,7 @@ GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
 package gplx.xowa.xtns.scribunto.libs; import gplx.*; import gplx.xowa.*; import gplx.xowa.xtns.*; import gplx.xowa.xtns.scribunto.*;
-import gplx.langs.regxs.*; import gplx.core.intls.*;
+import gplx.core.intls.*; import gplx.langs.regxs.*;
 import gplx.xowa.parsers.*;
 import gplx.xowa.xtns.scribunto.procs.*;
 public class Scrib_lib_ustring implements Scrib_lib {
@@ -118,30 +118,9 @@ public class Scrib_lib_ustring implements Scrib_lib {
 		AddCapturesFromMatch(tmp_list, regx_rslts[0], text, regx_converter.Capt_ary(), true);
 		return rslt.Init_many_list(tmp_list);
 	}
-	private Scrib_lib_ustring_gsub_mgr[] gsub_mgr_ary = Scrib_lib_ustring_gsub_mgr.Ary_empty;
-	private int gsub_mgr_max = 0, gsub_mgr_len = -1;
-	private final    Object gsub_mgr_lock = new Object();
 	public boolean Gsub(Scrib_proc_args args, Scrib_proc_rslt rslt) {
-		boolean rv = false;
-		synchronized (gsub_mgr_lock) {	// handle recursive gsub calls; PAGE:en.d:כלב; DATE:2016-01-22
-			Scrib_regx_converter regx_converter = new Scrib_regx_converter();
-			int new_len = gsub_mgr_len + 1;
-			if (new_len == gsub_mgr_max) {
-				this.gsub_mgr_max = new_len == 0 ? 2 : new_len * 2;
-				Scrib_lib_ustring_gsub_mgr[] new_gsub_mgr_ary = new Scrib_lib_ustring_gsub_mgr[gsub_mgr_max];
-				Array_.Copy(gsub_mgr_ary, new_gsub_mgr_ary);
-				gsub_mgr_ary = new_gsub_mgr_ary;
-			}
-			Scrib_lib_ustring_gsub_mgr cur = gsub_mgr_ary[new_len];
-			if (cur == null) {
-				cur = new Scrib_lib_ustring_gsub_mgr(core, regx_converter);
-				gsub_mgr_ary[new_len] = cur;
-			}
-			this.gsub_mgr_len = new_len;
-			rv = cur.Exec(args, rslt);
-			--gsub_mgr_len;
-		}
-		return rv;
+		Scrib_lib_ustring_gsub_mgr gsub_mgr = new Scrib_lib_ustring_gsub_mgr(core, new Scrib_regx_converter());
+		return gsub_mgr.Exec(args, rslt);
 	}
 	public boolean Gmatch_init(Scrib_proc_args args, Scrib_proc_rslt rslt) {
 		// String text = Scrib_kv_utl_.Val_to_str(values, 0);
@@ -195,189 +174,3 @@ public class Scrib_lib_ustring implements Scrib_lib {
 	private static final int Base1 = 1
 	, End_adj = 1;	// lua / php uses "end" as <= not <; EX: "abc" and bgn=0, end= 1; for XOWA, this is "a"; for MW / PHP it is "ab"
 }
-class Scrib_lib_ustring_gsub_mgr {
-	private Scrib_regx_converter regx_converter;
-	public Scrib_lib_ustring_gsub_mgr(Scrib_core core, Scrib_regx_converter regx_converter) {this.core = core; this.regx_converter = regx_converter;} private Scrib_core core; 
-	private byte tmp_repl_tid = Repl_tid_null; private byte[] tmp_repl_bry = null;
-	private Hash_adp repl_hash = null; private Scrib_lua_proc repl_func = null;
-	private int repl_count = 0;
-	public boolean Exec(Scrib_proc_args args, Scrib_proc_rslt rslt) {
-		Object text_obj = args.Cast_obj_or_null(0);
-		String text = String_.as_(text_obj);
-		if (text == null) text = Object_.Xto_str_strict_or_empty(text_obj);
-		String regx = args.Xstr_str_or_null(1);				// NOTE: @pattern sometimes int; PAGE:en.d:λύω; DATE:2014-09-02
-		if (args.Len() == 2) return rslt.Init_obj(text);	// if no replace arg, return self; PAGE:en.d:'orse; DATE:2013-10-13
-		Object repl_obj = args.Cast_obj_or_null(2);
-		regx = regx_converter.patternToRegex(Bry_.new_u8(regx), Scrib_regx_converter.Anchor_pow);
-		int limit = args.Cast_int_or(3, -1);
-		repl_count = 0;
-		Identify_repl(repl_obj);
-		String repl = Exec_repl(tmp_repl_tid, tmp_repl_bry, text, regx, limit);
-		return rslt.Init_many_objs(repl, repl_count);
-	}
-	private void Identify_repl(Object repl_obj) {
-		Class<?> repl_type = repl_obj.getClass();
-		if		(Object_.Eq(repl_type, String_.Cls_ref_type)) {
-			tmp_repl_tid = Repl_tid_string;
-			tmp_repl_bry = Bry_.new_u8((String)repl_obj);
-		}
-		else if	(Object_.Eq(repl_type, Int_.Cls_ref_type)) {	// NOTE:@replace sometimes int; PAGE:en.d:λύω; DATE:2014-09-02
-			tmp_repl_tid = Repl_tid_string;
-			tmp_repl_bry = Bry_.new_u8(Int_.To_str(Int_.Cast(repl_obj)));
-		}
-		else if	(Object_.Eq(repl_type, Keyval[].class)) {
-			tmp_repl_tid = Repl_tid_table;
-			Keyval[] repl_tbl = (Keyval[])repl_obj;
-			if (repl_hash == null) 
-				repl_hash = Hash_adp_.New();
-			else
-				repl_hash.Clear();
-			int repl_tbl_len = repl_tbl.length;
-			for (int i = 0; i < repl_tbl_len; i++) {
-				Keyval repl_itm = repl_tbl[i];
-				String repl_itm_val = repl_itm.Val_to_str_or_empty();
-				repl_hash.Add(repl_itm.Key(), Bry_.new_u8(repl_itm_val));
-			}
-		}
-		else if	(Object_.Eq(repl_type, Scrib_lua_proc.class)) {
-			tmp_repl_tid = Repl_tid_luacbk;
-			repl_func = (Scrib_lua_proc)repl_obj;
-		}
-		else if	(Object_.Eq(repl_type, Double_.Cls_ref_type)) {	// NOTE:@replace sometimes double; PAGE:de.v:Wikivoyage:Wikidata/Test_Modul:Wikidata2; DATE:2016-04-21
-			tmp_repl_tid = Repl_tid_string;
-			tmp_repl_bry = Bry_.new_u8(Double_.To_str(Double_.cast(repl_obj)));
-		}
-		else throw Err_.new_unhandled(Type_.Name(repl_type));
-	}
-	private String Exec_repl(byte repl_tid, byte[] repl_bry, String text, String regx, int limit) {
-		Regx_adp regx_mgr = Scrib_lib_ustring.RegxAdp_new_(core.Ctx(), regx);
-		Regx_match[] rslts = regx_mgr.Match_all(text, 0);
-		if (	rslts.length == 0				// PHP: If matches are found, the new subject will be returned, otherwise subject will be returned unchanged.; http://php.net/manual/en/function.preg-replace-callback.php
-			||	regx_mgr.Pattern_is_invalid()	// NOTE: invalid patterns should return self; EX:[^]; DATE:2014-09-02
-			) return text;	
-		rslts = regx_converter.Adjust_balanced(rslts);
-		Bry_bfr tmp_bfr = Bry_bfr_.New();
-		int len = rslts.length;
-		int pos = 0;
-		for (int i = 0; i < len; i++) {
-			if (limit > -1 && repl_count == limit) break;
-			Regx_match rslt = rslts[i];
-			tmp_bfr.Add_str_u8(String_.Mid(text, pos, rslt.Find_bgn()));	// NOTE: regx returns char pos (not bry); must add as String, not bry; DATE:2013-07-17
-			if (!Exec_repl_itm(tmp_bfr, repl_tid, repl_bry, text, rslt)) {	// will be false when gsub_proc returns nothing; PAGE:en.d:tracer PAGE:en.d:שלום DATE:2017-04-22;
-				tmp_bfr.Add_str_u8(String_.Mid(text, rslt.Find_bgn(), rslt.Find_end()));
-			}
-			pos = rslt.Find_end();
-			++repl_count;
-		}
-		int text_len = String_.Len(text);
-		if (pos < text_len)
-			tmp_bfr.Add_str_u8(String_.Mid(text, pos, text_len));			// NOTE: regx returns char pos (not bry); must add as String, not bry; DATE:2013-07-17
-		return tmp_bfr.To_str_and_clear();
-	}
-	private boolean Exec_repl_itm(Bry_bfr tmp_bfr, byte repl_tid, byte[] repl_bry, String text, Regx_match match) {
-		switch (repl_tid) {
-			case Repl_tid_string:
-				int len = repl_bry.length;
-				for (int i = 0; i < len; i++) {
-					byte b = repl_bry[i];
-					switch (b) {
-						case Byte_ascii.Percent: {
-							++i;
-							if (i == len)	// % at end of stream; just add %;
-								tmp_bfr.Add_byte(b);							
-							else {
-								b = repl_bry[i];
-								switch (b) {
-									case Byte_ascii.Num_0: case Byte_ascii.Num_1: case Byte_ascii.Num_2: case Byte_ascii.Num_3: case Byte_ascii.Num_4:
-									case Byte_ascii.Num_5: case Byte_ascii.Num_6: case Byte_ascii.Num_7: case Byte_ascii.Num_8: case Byte_ascii.Num_9:
-										int idx = b - Byte_ascii.Num_0;
-										if (idx == 0)	// NOTE: 0 means take result; REF.MW:if ($x === '0'); return $m[0]; PAGE:Wikipedia:Wikipedia_Signpost/Templates/Voter/testcases; DATE:2015-08-02
-											tmp_bfr.Add_str_u8(String_.Mid(text, match.Find_bgn(), match.Find_end()));											
-										else {			// NOTE: > 0 means get from groups if it exists; REF.MW:elseif (isset($m["m$x"])) return $m["m$x"]; PAGE:Wikipedia:Wikipedia_Signpost/Templates/Voter/testcases; DATE:2015-08-02
-											idx -= List_adp_.Base1;
-											if (idx < match.Groups().length) {	// retrieve numbered capture; TODO_OLD: support more than 9 captures
-												Regx_group grp = match.Groups()[idx];
-												tmp_bfr.Add_str_u8(String_.Mid(text, grp.Bgn(), grp.End()));	// NOTE: grp.Bgn() / .End() is for String pos (bry pos will fail for utf8 strings)
-											}
-											else {
-												tmp_bfr.Add_byte(Byte_ascii.Percent);
-												tmp_bfr.Add_byte(b);
-											}
-										}
-										break;
-									case Byte_ascii.Percent:
-										tmp_bfr.Add_byte(Byte_ascii.Percent);
-										break;
-									default:	// not a number; add literal
-										tmp_bfr.Add_byte(Byte_ascii.Percent);
-										tmp_bfr.Add_byte(b);	
-										break;
-								}
-							}
-							break;
-						}
-						default:
-							tmp_bfr.Add_byte(b);
-							break;
-					}
-				}
-				break;
-			case Repl_tid_table: {
-				int match_bgn = -1, match_end = -1;
-				Regx_group[] grps = match.Groups();
-				if (grps.length == 0) {
-					match_bgn = match.Find_bgn();
-					match_end = match.Find_end();
-				}
-				else {	// group exists, take first one (logic matches Scribunto); PAGE:en.w:Bannered_routes_of_U.S._Route_60; DATE:2014-08-15
-					Regx_group grp = grps[0];
-					match_bgn = grp.Bgn();
-					match_end = grp.End();
-				}
-				String find_str = String_.Mid(text, match_bgn, match_end);	// NOTE: rslt.Bgn() / .End() is for String pos (bry pos will fail for utf8 strings)
-				Object actl_repl_obj = repl_hash.Get_by(find_str);
-				if (actl_repl_obj == null)			// match found, but no replacement specified; EX:"abc", "[ab]", "a:A"; "b" in regex but not in tbl; EX:d:DVD; DATE:2014-03-31
-					tmp_bfr.Add_str_u8(find_str);
-				else
-					tmp_bfr.Add((byte[])actl_repl_obj);					
-				break;
-			}
-			case Repl_tid_luacbk: {
-				// TOMBSTONE: was causing garbled text on PAGE:en.w:Template:Infobox_kommune DATE:2018-07-02
-				/*
-				String find_str = String_.Mid(text, match.Find_bgn(), match.Find_end());
-				Keyval[] luacbk_args = Scrib_kv_utl_.base1_obj_(find_str); 
-				*/
-				Keyval[] luacbk_args = null;
-				Regx_group[] grps = match.Groups();
-				int grps_len = grps.length;
-				if (grps_len == 0) {	// no match; use original String
-					String find_str = String_.Mid(text, match.Find_bgn(), match.Find_end());
-					luacbk_args = Scrib_kv_utl_.base1_obj_(find_str);
-				}
-				else {					// match; build ary of matches; (see UStringLibrary.php)
-					luacbk_args = new Keyval[grps_len];
-					for (int i = 0; i < grps_len; i++) {
-						Regx_group grp = grps[i];
-						String find_str = String_.Mid(text, grp.Bgn(), grp.End());
-						luacbk_args[i] = Keyval_.int_(i + Scrib_core.Base_1, find_str);
-					}
-				}
-				/*
-				*/
-				Keyval[] rslts = core.Interpreter().CallFunction(repl_func.Id(), luacbk_args);
-				if (rslts.length == 0) // will be 0 when gsub_proc returns nil; PAGE:en.d:tracer; DATE:2017-04-22
-					return false;
-				else {									// ArrayIndex check
-					Object rslt_obj = rslts[0].Val();	// 0th idx has result
-					tmp_bfr.Add_str_u8(Object_.Xto_str_strict_or_empty(rslt_obj));	// NOTE: always convert to String; rslt_obj can be int; PAGE:en.d:seven DATE:2016-04-27
-				}
-				break;
-			}
-			default: throw Err_.new_unhandled(repl_tid);
-		}
-		return true;
-	}
-	private static final byte Repl_tid_null = 0, Repl_tid_string = 1, Repl_tid_table = 2, Repl_tid_luacbk = 3;
-	public static final    Scrib_lib_ustring_gsub_mgr[] Ary_empty = new Scrib_lib_ustring_gsub_mgr[0];
-}
diff --git a/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring__gsub__tst.java b/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring__gsub__tst.java
index f945bbf44..1b05c9ce0 100644
--- a/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring__gsub__tst.java
+++ b/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring__gsub__tst.java
@@ -14,7 +14,8 @@ GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
 package gplx.xowa.xtns.scribunto.libs; import gplx.*; import gplx.xowa.*; import gplx.xowa.xtns.*; import gplx.xowa.xtns.scribunto.*;
-import org.junit.*; import gplx.langs.regxs.*; import gplx.xowa.xtns.scribunto.engines.mocks.*;
+import org.junit.*; import gplx.core.tests.*;
+import gplx.langs.regxs.*; import gplx.xowa.xtns.scribunto.engines.mocks.*;	
 public class Scrib_lib_ustring__gsub__tst {
 	private final    Mock_scrib_fxt fxt = new Mock_scrib_fxt(); private Scrib_lib lib;
 	@Before public void init() {
@@ -30,6 +31,9 @@ public class Scrib_lib_ustring__gsub__tst {
 		// TOMBSTONE: tested with local MW and {{#invoke:Test|test16|a|[^]|b}} -> Lua error: Missing close-bracket for character set beginning at pattern character 1.; DATE:2018-07-02
 		// Exec_gsub("a"	, "[^]"			, 1, "b"		, "a;0");		// invalid regx should not fail; should return self; DATE:2013-10-20
 	}
+	@Test  public void Find__int() {// PURPOSE: gsub with integer arg should not fail; DATE:2013-11-06
+		fxt.Test__proc__kvps__flat(lib, Scrib_lib_ustring.Invk_gsub, Scrib_kv_utl_.base1_many_(1, "[1]", "2", 1), "2;1"); // NOTE: text is integer (lua / php are type-less)
+	}
 	@Test  public void Replace__none() {// PURPOSE: gsub with no replace argument should not fail; EX:d:'orse; DATE:2013-10-14
 		fxt.Test__proc__objs__flat(lib, Scrib_lib_ustring.Invk_gsub, Object_.Ary("text", "regx")						, "text");	// NOTE: repl, limit deliberately omitted
 	}
@@ -99,6 +103,20 @@ public class Scrib_lib_ustring__gsub__tst {
 		Tfds.Eq(Bool_.Y, Regx_adp_.Match("\0", "[\\x]"));	// \0 matched by any_char
 		Tfds.Eq(Bool_.Y, Regx_adp_.Match("\0", "[\\X]"));	// \0 matched by !any_char
 	}
+	@Test   public void Luacbk__basic() {
+		String text = "ad2f1e3z";
+		String regx = "([1d])([2e])([3f])";
+		Mock_proc__verify_args proc = new Mock_proc__verify_args(0, new Object[]{"B", "d", "2", "f"}, new Object[]{"Y", "1", "e", "3"});
+		fxt.Init__cbk(proc);
+		Exec_gsub(text, regx, -1, proc.To_scrib_lua_proc(), "aBYz;2");
+	}
+	@Test   public void Luacbk__anypos() {
+		String text = "ad2f1e3z";
+		String regx = "()([1d])([2e])([3f])"; // "()" is anypos, which inserts find_pos to results
+		Mock_proc__verify_args proc = new Mock_proc__verify_args(0, new Object[]{"B", 1, "d", "2", "f"}, new Object[]{"Y", 4, "1", "e", "3"});
+		fxt.Init__cbk(proc);
+		Exec_gsub(text, regx, -1, proc.To_scrib_lua_proc(), "aBYz;2");
+	}
 	private void Exec_gsub(String text, Object regx, int limit, Object repl, String expd) {
 		fxt.Test__proc__kvps__flat(lib, Scrib_lib_ustring.Invk_gsub, Scrib_kv_utl_.base1_many_(text, regx, repl, limit), expd);
 	}
@@ -133,3 +151,17 @@ class Mock_proc__empty extends Mock_proc_fxt {	private final    String find, rep
 		return String_.Eq(text, find) ? Keyval_.Ary(Keyval_.new_("0", repl)) : Keyval_.Ary_empty;
 	}
 }
+class Mock_proc__verify_args extends Mock_proc_fxt {	private final    Object[][] expd_ary;
+	private int expd_idx = -1;
+	public Mock_proc__verify_args(int id, Object[]... expd_ary) {super(id, "number");
+		this.expd_ary = expd_ary;
+	}
+	@Override public Keyval[] Exec_by_scrib(Keyval[] args) {
+		Object[] expd_args = expd_ary[++expd_idx];
+		Object rv = expd_args[0];
+		expd_args = (Object[])Array_.Extract_by_pos(expd_args, 1);
+		Object[] actl_args = Keyval_.Ary__to_objary__val(args);
+		Gftest.Eq__ary(expd_args, actl_args, "failed lua_cbk");
+		return Keyval_.Ary(Keyval_.int_(0, rv));
+	}
+}
diff --git a/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring_gsub_mgr.java b/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring_gsub_mgr.java
new file mode 100644
index 000000000..6377961c9
--- /dev/null
+++ b/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_lib_ustring_gsub_mgr.java
@@ -0,0 +1,235 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.xowa.xtns.scribunto.libs; import gplx.*; import gplx.xowa.*; import gplx.xowa.xtns.*; import gplx.xowa.xtns.scribunto.*;
+import gplx.langs.regxs.*;
+import gplx.xowa.xtns.scribunto.procs.*;
+class Scrib_lib_ustring_gsub_mgr {
+	private final    Scrib_core core;
+	private final    Scrib_regx_converter regx_converter;
+	private byte[] repl_bry; private Hash_adp repl_hash; private Scrib_lua_proc repl_func;
+	private int repl_count = 0;
+	public Scrib_lib_ustring_gsub_mgr(Scrib_core core, Scrib_regx_converter regx_converter) {
+		this.core = core;
+		this.regx_converter = regx_converter;
+	}
+	public boolean Exec(Scrib_proc_args args, Scrib_proc_rslt rslt) {
+		// get @text; NOTE: sometimes int; DATE:2013-11-06
+		String text = args.Xstr_str_or_null(0);
+		if (args.Len() == 2) return rslt.Init_obj(text); // if no @replace, return @text; PAGE:en.d:'orse; DATE:2013-10-13
+
+		// get @pattern; NOTE: sometimes int; PAGE:en.d:λύω; DATE:2014-09-02
+		String regx = args.Xstr_str_or_null(1);
+		regx = regx_converter.patternToRegex(Bry_.new_u8(regx), Scrib_regx_converter.Anchor_pow);
+
+		// get @repl
+		Object repl_obj = args.Cast_obj_or_null(2);
+		byte repl_tid = Identify_repl(repl_obj);
+
+		// get @limit; reset repl_count
+		int limit = args.Cast_int_or(3, -1);
+		repl_count = 0;
+
+		// do repl
+		String repl = Exec_repl(repl_tid, text, regx, limit);
+		return rslt.Init_many_objs(repl, repl_count);
+	}
+	private byte Identify_repl(Object repl_obj) {
+		byte repl_tid = Repl_tid_null;
+		// @repl can be String, int, table, func
+		Class<?> repl_type = repl_obj.getClass();
+		if		(Object_.Eq(repl_type, String_.Cls_ref_type)) {
+			repl_tid = Repl_tid_string;
+			repl_bry = Bry_.new_u8((String)repl_obj);
+		}
+		else if	(Object_.Eq(repl_type, Int_.Cls_ref_type)) {	// NOTE:@replace sometimes int; PAGE:en.d:λύω; DATE:2014-09-02
+			repl_tid = Repl_tid_string;
+			repl_bry = Bry_.new_u8(Int_.To_str(Int_.Cast(repl_obj)));
+		}
+		else if	(Object_.Eq(repl_type, Keyval[].class)) {
+			repl_tid = Repl_tid_table;
+			repl_hash = Hash_adp_.New();
+			Keyval[] kvs = (Keyval[])repl_obj;
+			int kvs_len = kvs.length;
+			for (int i = 0; i < kvs_len; i++) {
+				Keyval kv = kvs[i];
+				repl_hash.Add(kv.Key(), Bry_.new_u8(kv.Val_to_str_or_empty()));
+			}
+		}
+		else if	(Object_.Eq(repl_type, Scrib_lua_proc.class)) {
+			repl_tid = Repl_tid_luacbk;
+			repl_func = (Scrib_lua_proc)repl_obj;
+		}
+		else if	(Object_.Eq(repl_type, Double_.Cls_ref_type)) {	// NOTE:@replace sometimes double; PAGE:de.v:Wikivoyage:Wikidata/Test_Modul:Wikidata2; DATE:2016-04-21
+			repl_tid = Repl_tid_string;
+			repl_bry = Bry_.new_u8(Double_.To_str(Double_.cast(repl_obj)));
+		}
+		else
+			throw Err_.new_unhandled(Type_.Name(repl_type));
+		return repl_tid;
+	}
+	private String Exec_repl(byte repl_tid, String text, String regx, int limit) {
+		// parse regx
+		Regx_adp regx_mgr = Scrib_lib_ustring.RegxAdp_new_(core.Ctx(), regx);
+		if (regx_mgr.Pattern_is_invalid()) return text; // NOTE: invalid patterns should return self; EX:[^]; DATE:2014-09-02)
+
+		// exec regx
+		Regx_match[] rslts = regx_mgr.Match_all(text, 0);
+		if (rslts.length == 0) return text; // PHP: If matches are found, the new subject will be returned, otherwise subject will be returned unchanged.; http://php.net/manual/en/function.preg-replace-callback.php
+		rslts = regx_converter.Adjust_balanced(rslts);
+
+		Bry_bfr tmp_bfr = Bry_bfr_.New();
+		int rslts_len = rslts.length;
+		int text_pos = 0;
+		for (int i = 0; i < rslts_len; i++) {
+			if (repl_count == limit) break; // stop if repl_count reaches limit; note that limit = -1 by default, unless specified
+
+			// add text up to find.bgn
+			Regx_match rslt = rslts[i];
+			tmp_bfr.Add_str_u8(String_.Mid(text, text_pos, rslt.Find_bgn()));	// NOTE: regx returns char text_pos (not bry); must add as String, not bry; DATE:2013-07-17
+			
+			// replace result
+			if (!Exec_repl_itm(tmp_bfr, repl_tid, text, rslt)) {
+				// will be false when gsub_proc returns nothing; PAGE:en.d:tracer PAGE:en.d:שלום DATE:2017-04-22;
+				tmp_bfr.Add_str_u8(String_.Mid(text, rslt.Find_bgn(), rslt.Find_end()));
+			}
+
+			// update
+			text_pos = rslt.Find_end();
+			repl_count++;
+		}
+
+		// add rest of String
+		int text_len = String_.Len(text);
+		if (text_pos < text_len)
+			tmp_bfr.Add_str_u8(String_.Mid(text, text_pos, text_len));			// NOTE: regx returns char text_pos (not bry); must add as String, not bry; DATE:2013-07-17
+		return tmp_bfr.To_str_and_clear();
+	}
+	private boolean Exec_repl_itm(Bry_bfr tmp_bfr, byte repl_tid, String text, Regx_match match) {
+		switch (repl_tid) {
+			case Repl_tid_string:
+				int len = repl_bry.length;
+				for (int i = 0; i < len; i++) {
+					byte b = repl_bry[i];
+					switch (b) {
+						case Byte_ascii.Percent: {
+							++i;
+							if (i == len)	// % at end of stream; just add %;
+								tmp_bfr.Add_byte(b);							
+							else {
+								b = repl_bry[i];
+								switch (b) {
+									case Byte_ascii.Num_0: case Byte_ascii.Num_1: case Byte_ascii.Num_2: case Byte_ascii.Num_3: case Byte_ascii.Num_4:
+									case Byte_ascii.Num_5: case Byte_ascii.Num_6: case Byte_ascii.Num_7: case Byte_ascii.Num_8: case Byte_ascii.Num_9:
+										int idx = b - Byte_ascii.Num_0;
+										if (idx == 0)	// NOTE: 0 means take result; REF.MW:if ($x === '0'); return $m[0]; PAGE:Wikipedia:Wikipedia_Signpost/Templates/Voter/testcases; DATE:2015-08-02
+											tmp_bfr.Add_str_u8(String_.Mid(text, match.Find_bgn(), match.Find_end()));											
+										else {			// NOTE: > 0 means get from groups if it exists; REF.MW:elseif (isset($m["m$x"])) return $m["m$x"]; PAGE:Wikipedia:Wikipedia_Signpost/Templates/Voter/testcases; DATE:2015-08-02
+											idx -= List_adp_.Base1;
+											if (idx < match.Groups().length) {	// retrieve numbered capture; TODO_OLD: support more than 9 captures
+												Regx_group grp = match.Groups()[idx];
+												tmp_bfr.Add_str_u8(String_.Mid(text, grp.Bgn(), grp.End()));	// NOTE: grp.Bgn() / .End() is for String pos (bry pos will fail for utf8 strings)
+											}
+											else {
+												tmp_bfr.Add_byte(Byte_ascii.Percent);
+												tmp_bfr.Add_byte(b);
+											}
+										}
+										break;
+									case Byte_ascii.Percent:
+										tmp_bfr.Add_byte(Byte_ascii.Percent);
+										break;
+									default:	// not a number; add literal
+										tmp_bfr.Add_byte(Byte_ascii.Percent);
+										tmp_bfr.Add_byte(b);	
+										break;
+								}
+							}
+							break;
+						}
+						default:
+							tmp_bfr.Add_byte(b);
+							break;
+					}
+				}
+				break;
+			case Repl_tid_table: {
+				int match_bgn = -1, match_end = -1;
+				Regx_group[] grps = match.Groups();
+				if (grps.length == 0) {
+					match_bgn = match.Find_bgn();
+					match_end = match.Find_end();
+				}
+				else {	// group exists, take first one (logic matches Scribunto); PAGE:en.w:Bannered_routes_of_U.S._Route_60; DATE:2014-08-15
+					Regx_group grp = grps[0];
+					match_bgn = grp.Bgn();
+					match_end = grp.End();
+				}
+				String find_str = String_.Mid(text, match_bgn, match_end);	// NOTE: rslt.Bgn() / .End() is for String pos (bry pos will fail for utf8 strings)
+				Object actl_repl_obj = repl_hash.Get_by(find_str);
+				if (actl_repl_obj == null)			// match found, but no replacement specified; EX:"abc", "[ab]", "a:A"; "b" in regex but not in tbl; EX:d:DVD; DATE:2014-03-31
+					tmp_bfr.Add_str_u8(find_str);
+				else
+					tmp_bfr.Add((byte[])actl_repl_obj);					
+				break;
+			}
+			case Repl_tid_luacbk: {
+				Keyval[] luacbk_args = null;
+				Regx_group[] grps = match.Groups();
+				int grps_len = grps.length;
+				// no grps; pass 1 arg based on @match: EX: ("ace", "[b-d]"); args -> ("c")
+				if (grps_len == 0) {
+					String find_str = String_.Mid(text, match.Find_bgn(), match.Find_end());
+					luacbk_args = Scrib_kv_utl_.base1_obj_(find_str);
+				}
+				// grps exist; pass n args based on grp[n].match; EX: ("acfg", "([b-d])([e-g])"); args -> ("c", "f")
+				else {
+					// memoize any_pos args for loop
+					boolean any_pos = regx_converter.Any_pos();
+					Keyval[] capt_ary = regx_converter.Capt_ary();
+					int capt_ary_len = capt_ary.length;
+
+					// loop grps; for each grp, create corresponding arg in luacbk
+					luacbk_args = new Keyval[grps_len];
+					for (int i = 0; i < grps_len; i++) {
+						Regx_group grp = grps[i];
+
+						// anypos will create @offset arg; everything else creates a @match arg based on grp
+						Object val = any_pos && i < capt_ary_len && Bool_.Cast(capt_ary[i].Val())
+								? (Object)grp.Bgn()
+								: (Object)String_.Mid(text, grp.Bgn(), grp.End());
+						luacbk_args[i] = Keyval_.int_(i + Scrib_core.Base_1, val);
+					}
+				}
+
+				// do callback
+				Keyval[] rslts = core.Interpreter().CallFunction(repl_func.Id(), luacbk_args);
+
+				// eval result
+				if (rslts.length == 0) // will be 0 when gsub_proc returns nil; PAGE:en.d:tracer; DATE:2017-04-22
+					return false;
+				else {									// ArrayIndex check
+					Object rslt_obj = rslts[0].Val();	// 0th idx has result
+					tmp_bfr.Add_str_u8(Object_.Xto_str_strict_or_empty(rslt_obj));	// NOTE: always convert to String; rslt_obj can be int; PAGE:en.d:seven DATE:2016-04-27
+				}
+				break;
+			}
+			default: throw Err_.new_unhandled(repl_tid);
+		}
+		return true;
+	}
+	private static final byte Repl_tid_null = 0, Repl_tid_string = 1, Repl_tid_table = 2, Repl_tid_luacbk = 3;
+	public static final    Scrib_lib_ustring_gsub_mgr[] Ary_empty = new Scrib_lib_ustring_gsub_mgr[0];
+}
diff --git a/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_regx_converter.java b/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_regx_converter.java
index 02d7f2976..112ee5c41 100644
--- a/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_regx_converter.java
+++ b/400_xowa/src/gplx/xowa/xtns/scribunto/libs/Scrib_regx_converter.java
@@ -37,6 +37,8 @@ public class Scrib_regx_converter {
 		int len = pat.length;
 		int grps_len = 0;
 		int bct = 0;
+
+		// REF.MW: https://github.com/wikimedia/mediawiki-extensions-Scribunto/blob/master/includes/engines/LuaCommon/UstringLibrary.php#L415
 		for (int i = 0; i < len; i++) {
 			int i_end = i + 1;
 			q_flag = false; // must be reset; REF.MW:UstringLibrary.php|patternToRegex; DATE:2014-02-08
@@ -44,24 +46,28 @@ public class Scrib_regx_converter {
 			switch (cur) {
 				case Byte_ascii.Pow:
 					q_flag = i != 0;
-					bfr.Add((anchor == Anchor_null || q_flag) ? Bry_pow_escaped : anchor);	// NOTE: must add anchor \G when using offsets; EX:cs.n:Category:1._zárí_2008; DATE:2014-05-07
+					bfr.Add((anchor == Anchor_null || q_flag) ? Bry_pow_escaped : anchor); // NOTE: must add anchor \G when using offsets; EX:cs.n:Category:1._zárí_2008; DATE:2014-05-07
 					break;
 				case Byte_ascii.Dollar:
 					q_flag = i < len - 1;
 					bfr.Add(q_flag ? Bry_dollar_escaped : Bry_dollar_literal);
 					break;
 				case Byte_ascii.Paren_bgn: {
+					// fail if "(EOS"
 					if (i + 1 >= len)
 						throw Err_.new_wo_type("Unmatched open-paren at pattern character " + Int_.To_str(i_end));
 					int grp_idx = grp_mgr.Capt__len() + 1;
-					boolean is_empty_capture = pat[i + 1] == Byte_ascii.Paren_end;	// current is "()"
+
+					// check for "()"; enables anypos flag
+					boolean is_empty_capture = pat[i + 1] == Byte_ascii.Paren_end;
 					if (is_empty_capture)
 						any_pos = true;
-					bfr.Add_byte(Byte_ascii.Paren_bgn); // $re .= "(?<m$n>";
 					grp_mgr.Capt__add__real(grp_idx, is_empty_capture);
+					bfr.Add_byte(Byte_ascii.Paren_bgn); // $re .= "(?<m$n>";
 					break;
 				}
 				case Byte_ascii.Paren_end:
+					// fail if ")" without preceding "("
 					if (grp_mgr.Open__len() <= 0)
 						throw Err_.new_wo_type("Unmatched close-paren at pattern character " + Int_.To_str(i_end));
 					grp_mgr.Open__pop();