diff --git a/C/c_interface.c b/C/c_interface.c
index 885197e30..a93f63a96 100644
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -1781,7 +1781,7 @@ YAP_EndConsult(void)
 X_API Term
 YAP_Read(int (*mygetc)(void))
 {
-  Term t;
+  Term t, tpos = TermNil;
   int sno;
   TokEntry *tokstart;
   
@@ -1794,7 +1794,8 @@ YAP_Read(int (*mygetc)(void))
     return TermNil;
   }
   Stream[sno].stream_getc = do_yap_getc;
-  tokstart = Yap_tokptr = Yap_toktide = Yap_tokenizer(sno);
+  Stream[sno].status |= Tty_Stream_f;
+  tokstart = Yap_tokptr = Yap_toktide = Yap_tokenizer(sno, &tpos);
   Stream[sno].status = Free_Stream_f;
   if (Yap_ErrorMessage)
     {
diff --git a/C/init.c b/C/init.c
index c576607f9..679b4167a 100644
--- a/C/init.c
+++ b/C/init.c
@@ -946,7 +946,7 @@ InitFlags(void)
   yap_flags[LANGUAGE_MODE_FLAG] = 0;
   yap_flags[STRICT_ISO_FLAG] = FALSE;
   yap_flags[SOURCE_MODE_FLAG] = FALSE;
-  yap_flags[CHARACTER_ESCAPE_FLAG] = SICSTUS_CHARACTER_ESCAPES;
+  yap_flags[CHARACTER_ESCAPE_FLAG] = ISO_CHARACTER_ESCAPES;
   yap_flags[WRITE_QUOTED_STRING_FLAG] = FALSE;
 #if (defined(YAPOR) || defined(THREADS)) && PUREe_YAPOR
   yap_flags[ALLOW_ASSERTING_STATIC_FLAG] = FALSE;
diff --git a/C/iopreds.c b/C/iopreds.c
index 78b9e2c4c..b5be01515 100644
--- a/C/iopreds.c
+++ b/C/iopreds.c
@@ -3827,8 +3827,7 @@ static Int
       old_H = H;
       Yap_eot_before_eof = FALSE;
       tpos = StreamPosition(inp_stream);
-      StartLine = Stream[inp_stream].linecount;
-      tokstart = Yap_tokptr = Yap_toktide = Yap_tokenizer(inp_stream);
+      tokstart = Yap_tokptr = Yap_toktide = Yap_tokenizer(inp_stream, &tpos);
       if (Yap_Error_TYPE != YAP_NO_ERROR && seekable) {
 	H = old_H;
 	Yap_clean_tokenizer(tokstart, Yap_VarTable, Yap_AnonVarTable);
@@ -4181,13 +4180,19 @@ StreamPosition(int sno)
     else
       sargs[0] = MkIntTerm (YP_ftell (Stream[sno].u.file.file));
   }
-  sargs[1] = MkIntegerTerm (Stream[sno].linecount);
+  sargs[1] = MkIntegerTerm (StartLine = Stream[sno].linecount);
   sargs[2] = MkIntegerTerm (Stream[sno].linepos);
   sargs[3] = sargs[4] = MkIntTerm (0);
   return Yap_MkApplTerm (FunctorStreamPos, 5, sargs);
 }
 
 
+Term
+Yap_StreamPosition(int sno)
+{
+  return StreamPosition(sno);
+}
+
 static Int
 p_show_stream_position (void)
 {				/* '$show_stream_position'(+Stream,Pos) */
@@ -5971,12 +5976,13 @@ Yap_StringToTerm(char *s,Term *tp)
   Term t;
   TokEntry *tokstart;
   tr_fr_ptr TR_before_parse;
+  Term tpos = TermNil;
 
   if (sno < 0)
     return FALSE;
   UNLOCK(Stream[sno].streamlock);
   TR_before_parse = TR;
-  tokstart = Yap_tokptr = Yap_toktide = Yap_tokenizer(sno);
+  tokstart = Yap_tokptr = Yap_toktide = Yap_tokenizer(sno, &tpos);
   if (tokstart == NIL && tokstart->Tok == Ord (eot_tok)) {
     if (tp) {
       *tp = MkAtomTerm(Yap_LookupAtom("end of file found before end of term"));
diff --git a/C/readutil.c b/C/readutil.c
index 3f021d74a..52b910ea2 100644
--- a/C/readutil.c
+++ b/C/readutil.c
@@ -145,13 +145,13 @@ static Int
 p_stream_to_terms(void)
 {
   int sno = Yap_CheckStream (ARG1, Input_Stream_f, "read_line_to_codes/2");
-  Term t = Deref(ARG3);
+  Term t = Deref(ARG3), tpos = TermNil;
 
   if (sno < 0)
     return FALSE;
   while (!(Stream[sno].status & Eof_Stream_f)) {
     /* skip errors */
-    TokEntry *tokstart = Yap_tokptr = Yap_toktide = Yap_tokenizer(sno);
+    TokEntry *tokstart = Yap_tokptr = Yap_toktide = Yap_tokenizer(sno, &tpos);
     if (!Yap_ErrorMessage)
     {
       Term th = Yap_Parse();
diff --git a/C/scanner.c b/C/scanner.c
index 13c6d08a9..a63f6d9ea 100644
--- a/C/scanner.c
+++ b/C/scanner.c
@@ -732,7 +732,7 @@ ch_to_wide(char *base, char *charp)
 }
 
 TokEntry *
-Yap_tokenizer(int inp_stream)
+Yap_tokenizer(int inp_stream, Term *tposp)
 {
   TokEntry *t, *l, *p;
   enum TokenKinds kind;
@@ -753,6 +753,10 @@ Yap_tokenizer(int inp_stream)
   p = NULL;			/* Just to make lint happy */
   LOCK(Stream[inp_stream].streamlock);
   ch = Nxtch(inp_stream);
+  while (chtype(ch) == BS) {
+    ch = Nxtch(inp_stream);
+  }
+  *tposp = Yap_StreamPosition(inp_stream);
   do {
     wchar_t och;
     int quote, isvar;
@@ -789,6 +793,13 @@ Yap_tokenizer(int inp_stream)
       while ((ch = Nxtch(inp_stream)) != 10 && chtype(ch) != EF);
       if (chtype(ch) != EF) {
 	/* blank space */
+	if (t == l) {
+	  /* we found a comment before reading characters */
+	  while (chtype(ch) == BS) {
+	    ch = Nxtch(inp_stream);
+	  }
+	  *tposp = Yap_StreamPosition(inp_stream);
+	}
 	goto restart;
       } else {
 	t->Tok = Ord(kind = eot_tok);
@@ -1114,6 +1125,13 @@ Yap_tokenizer(int inp_stream)
 	  t->Tok = Ord(kind = eot_tok);
 	}
 	ch = Nxtch(inp_stream);
+	if (t == l) {
+	  /* we found a comment before reading characters */
+	  while (chtype(ch) == BS) {
+	    ch = Nxtch(inp_stream);
+	  }
+	  *tposp = Yap_StreamPosition(inp_stream);
+	}
 	goto restart;
       }
     enter_symbol:
diff --git a/C/write.c b/C/write.c
index acd4c7f0e..f0f144df0 100644
--- a/C/write.c
+++ b/C/write.c
@@ -178,17 +178,18 @@ legalAtom(unsigned char *s)			/* Is this a legal atom ? */
     else if (Yap_chtype[ch] == SL)
       return (!*++s);
     else if ((ch == ',' || ch == '.') && !s[1])
-      return (FALSE);
+      return FALSE;
     else
       while (ch) {
-	if (Yap_chtype[ch] != SY) return (FALSE);
+	if (Yap_chtype[ch] != SY || ch == '\\')
+	  return FALSE;
 	ch = *++s;
       }
-    return (TRUE);
+    return TRUE;
   } else
     while ((ch = *++s) != 0)
       if (Yap_chtype[ch] > NU)
-	return (FALSE);
+	return FALSE;
   return (TRUE);
 }
 
@@ -219,6 +220,73 @@ AtomIsSymbols(unsigned char *s)		/* Is this atom just formed by symbols ? */
   return(symbol);
 }
 
+static void
+write_quoted(int ch, int quote, wrf writewch)
+{
+  if (yap_flags[CHARACTER_ESCAPE_FLAG] == CPROLOG_CHARACTER_ESCAPES) {
+    wrputc(ch, writewch);
+    if (ch == '\'')
+      wrputc('\'', writewch);	/* be careful about quotes */
+    return;
+  }
+  if (!(ch < 0xff  && chtype(ch) == BS) && ch != '\'' && ch != '\\') {
+    wrputc(ch, writewch);
+  } else {
+    switch (ch) {
+    case '\\':
+    case '\'':
+      wrputc('\\', writewch);	
+      wrputc(ch, writewch);	
+      break;
+    case 7:
+      wrputc('\\', writewch);	
+      wrputc('a', writewch);	
+      break;
+    case '\b':
+      wrputc('\\', writewch);
+      wrputc('b', writewch);	
+      break;
+    case '\t':
+      wrputc('\\', writewch);
+      wrputc('t', writewch);	
+      break;
+    case ' ':
+    case 160:
+      wrputc(' ', writewch);
+      break;
+    case '\n':
+      wrputc('\\', writewch);
+      wrputc('n', writewch);	
+      break;
+    case 11:
+      wrputc('\\', writewch);
+      wrputc('v', writewch);	
+      break;
+    case '\r':
+      wrputc('\\', writewch);
+      wrputc('r', writewch);	
+      break;
+    case '\f':
+      wrputc('\\', writewch);
+      wrputc('f', writewch);	
+      break;
+    default:
+      if ( ch <= 0xff ) {
+	char esc[8];
+	
+	if (yap_flags[CHARACTER_ESCAPE_FLAG] == SICSTUS_CHARACTER_ESCAPES) {
+	  sprintf(esc, "\\%03o", ch);
+	} else {
+	  /* last backslash in ISO mode */
+	  sprintf(esc, "\\%03o\\", ch);
+	}
+	wrputs(esc, writewch);
+      }
+    }
+  }
+}
+
+
 static void 
 putAtom(Atom atom, int Quote_illegal, wrf writewch)			/* writes an atom	 */
 	                     
@@ -242,11 +310,7 @@ putAtom(Atom atom, int Quote_illegal, wrf writewch)			/* writes an atom	 */
       wrputc('\'', writewch);
       while (*ws) {
 	wchar_t ch = *ws++;
-	wrputc(ch, writewch);
-	if (ch == '\\' && yap_flags[CHARACTER_ESCAPE_FLAG] != CPROLOG_CHARACTER_ESCAPES)
-	  wrputc('\\', writewch);	/* be careful about backslashes */
-	else if (ch == '\'')
-	  wrputc('\'', writewch);	/* be careful about quotes */
+	write_quoted(ch, '\'', writewch);
       }
       wrputc('\'', writewch);
     } else {
@@ -261,11 +325,7 @@ putAtom(Atom atom, int Quote_illegal, wrf writewch)			/* writes an atom	 */
     wrputc('\'', writewch);
     while (*s) {
       wchar_t ch = *s++;
-      wrputc(ch, writewch);
-      if (ch == '\\' && yap_flags[CHARACTER_ESCAPE_FLAG] != CPROLOG_CHARACTER_ESCAPES)
-	wrputc('\\', writewch);	/* be careful about backslashes */
-      else if (ch == '\'')
-	wrputc('\'', writewch);	/* be careful about quotes */
+      write_quoted(ch, '\'', writewch);
     }
     wrputc('\'', writewch);
   } else {
@@ -276,7 +336,8 @@ putAtom(Atom atom, int Quote_illegal, wrf writewch)			/* writes an atom	 */
 static int 
 IsStringTerm(Term string)	/* checks whether this is a string */
 {
-  if (IsVarTerm(string)) return(FALSE);
+  if (IsVarTerm(string))
+    return FALSE;
   do {
     Term hd;
     int ch;
@@ -301,12 +362,7 @@ putString(Term string, wrf writewch)		/* writes a string	 */
   wrputc('"', writewch);
   while (string != TermNil) {
     int ch = IntOfTerm(HeadOfTerm(string));
-    wrputc(ch, writewch);
-    if (ch == '\\' && yap_flags[CHARACTER_ESCAPE_FLAG] != CPROLOG_CHARACTER_ESCAPES)
-      wrputc('\\', writewch);	/* be careful about backslashes */
-    else if (ch == '"')
-      wrputc('"', writewch);	/* be careful about quotes */
-    string = TailOfTerm(string);
+    write_quoted(ch, '"', writewch);
   }
   wrputc('"', writewch);
   lastw = alphanum;
diff --git a/CLPBN/Makefile.in b/CLPBN/Makefile.in
index 60e820cef..64dfd8456 100644
--- a/CLPBN/Makefile.in
+++ b/CLPBN/Makefile.in
@@ -52,6 +52,7 @@ CLPBN_PROGRAMS= \
 
 CLPBN_LEARNING_PROGRAMS= \
 	$(CLPBN_LEARNING_SRCDIR)/bnt_parms.yap \
+	$(CLPBN_LEARNING_SRCDIR)/em.yap \
 	$(CLPBN_LEARNING_SRCDIR)/learn_utils.yap \
 	$(CLPBN_LEARNING_SRCDIR)/mle.yap
 
diff --git a/CLPBN/learning/em.yap b/CLPBN/learning/em.yap
index 01a370506..5cf154af7 100644
--- a/CLPBN/learning/em.yap
+++ b/CLPBN/learning/em.yap
@@ -16,6 +16,9 @@
 	       empty_dist/2,
 	       dist_new_table/2]).
 
+:- use_module(library('clpbn/connected'),
+	      [clpbn_subgraphs/2]).
+
 :- use_module(library('clpbn/learning/learn_utils'),
 	      [run_all/1,
 	       clpbn_vars/2,
@@ -29,8 +32,10 @@
 	      [matrix_add/3,
 	       matrix_to_list/2]).
 
-:- use_module(library('clpbn/utils'), [
-	check_for_hidden_vars/3]).
+:- use_module(library('clpbn/utils'),
+	      [
+	       check_for_hidden_vars/3,
+	       sort_vars_by_key/3]).
 
 :- meta_predicate em(:,+,+,-,-), init_em(:,-).
 
@@ -50,8 +55,9 @@ em(Items, MaxError, MaxIts, Tables, Likelihood) :-
 init_em(Items, state(AllVars, AllDists, AllDistInstances, MargVars)) :-
 	run_all(Items),
 	attributes:all_attvars(AllVars0),
+	sort_vars_by_key(AllVars0,AllVars1,[]),
 	% remove variables that do not have to do with this query.
-	check_for_hidden_vars(AllVars0, AllVars0, AllVars),
+	check_for_hidden_vars(AllVars1, AllVars1, AllVars),
 	different_dists(AllVars, AllDists, AllDistInstances, MargVars),
 	clpbn_init_solver(MargVars, AllVars, _).
 
@@ -59,6 +65,8 @@ init_em(Items, state(AllVars, AllDists, AllDistInstances, MargVars)) :-
 em_loop(Its, Likelihood0, State, MaxError, MaxIts, LikelihoodF, FTables) :-
 	estimate(State, LPs),
 	maximise(State, Tables, LPs, Likelihood),
+	(recorded(clpbn_dist_db, DB, _), writeln(DB), fail ; true),
+	writeln(Likelihood:Tables),
 	(
 	    (
 	     (Likelihood - Likelihood0)/Likelihood < MaxError
diff --git a/CLPBN/learning/example/school_params.yap b/CLPBN/learning/example/school_params.yap
index a2ced93ee..abe26f891 100644
--- a/CLPBN/learning/example/school_params.yap
+++ b/CLPBN/learning/example/school_params.yap
@@ -28,7 +28,5 @@ goal(student_intelligence(P,V)) :-
 goal(course_difficulty(P,V)) :-
         pos:course_difficulty(P,V1),
         ( random > 0.1 -> V = V1 ; true).
-/*
 goal(registration_satisfaction(P,V)) :-
         pos:registration_satisfaction(P,V).
-*/
diff --git a/CLPBN/learning/learn_utils.yap b/CLPBN/learning/learn_utils.yap
index a6833684a..03d96a4a7 100644
--- a/CLPBN/learning/learn_utils.yap
+++ b/CLPBN/learning/learn_utils.yap
@@ -54,8 +54,6 @@ normalise_counts(MAT,NMAT) :-
 	matrix_op_to_lines(MAT, Sum, /, NMAT).
 
 compute_likelihood(Table0, NewTable, DeltaLik) :-
-	matrix:matrix_to_list(Table0,L0), writeln(L0),
-	matrix:matrix_to_list(NewTable,L1), writeln(L1),
 	matrix_to_logs(NewTable, Logs),
 	matrix_op(Table0, Logs, *, Logs),
 	matrix_sum(Logs, DeltaLik).
diff --git a/H/iopreds.h b/H/iopreds.h
index f8033ac9a..2bf2ec26a 100644
--- a/H/iopreds.h
+++ b/H/iopreds.h
@@ -135,6 +135,7 @@ StreamDesc;
 #define ALIASES_BLOCK_SIZE 8
 
 void STD_PROTO (Yap_InitStdStreams, (void));
+Term STD_PROTO (Yap_StreamPosition, (int));
 
 EXTERN inline int
 GetCurInpPos (int inp_stream)
diff --git a/H/yapio.h b/H/yapio.h
index e60bb039c..65a374487 100644
--- a/H/yapio.h
+++ b/H/yapio.h
@@ -283,7 +283,7 @@ VarEntry STD_PROTO(*Yap_LookupVar,(char *));
 Term STD_PROTO(Yap_VarNames,(VarEntry *,Term));
 
 /* routines in scanner.c */
-TokEntry STD_PROTO(*Yap_tokenizer,(int));
+TokEntry STD_PROTO(*Yap_tokenizer,(int, Term *));
 void     STD_PROTO(Yap_clean_tokenizer,(TokEntry *, VarEntry *, VarEntry *));
 Term     STD_PROTO(Yap_scan_num,(int (*)(int)));
 char	 STD_PROTO(*Yap_AllocScannerMemory,(unsigned int));
diff --git a/library/rltree/range_list.c b/library/rltree/range_list.c
index f4bccb399..4a74aca95 100644
--- a/library/rltree/range_list.c
+++ b/library/rltree/range_list.c
@@ -56,6 +56,11 @@ static void root_intervals(RL_Tree* tree);
 NUM next_min(RL_Tree *tree,NUM node,NUM node_num,NUM interval,NUM max,NUM min);
 NUM tree_minus(RL_Tree *r1,RL_Tree *r2,NUM node1,NUM node2,NUM node_num,NUM interval,NUM max);
 
+RL_Tree* minus_rl(RL_Tree* range1,RL_Tree* range2);
+void shift_right(RL_Tree *tree,const NUM idx,const long nnodes);
+void shift_left(RL_Tree *tree,const NUM idx, const long nnodes);
+void intersect_leafs(char *storage1,char *storage2);
+
 static void print_nodes(RL_Tree* tree);
 
 //
diff --git a/library/rltree/yap_rl.c b/library/rltree/yap_rl.c
index 2894d2795..43d7c91d4 100644
--- a/library/rltree/yap_rl.c
+++ b/library/rltree/yap_rl.c
@@ -116,7 +116,7 @@ static
 int 
 p_rl_size(void) {
 
-  YAP_Term t1=YAP_Deref(YAP_ARG1),t2=YAP_Deref(YAP_ARG2),t_size;
+  YAP_Term t1=YAP_Deref(YAP_ARG1),t_size;
   IDTYPE id;
   RL_Tree* tree;
   unsigned int size;
@@ -129,7 +129,7 @@ p_rl_size(void) {
   
   size=tree->size*sizeof(RL_Node)+sizeof(RL_Tree);
   t_size=YAP_MkIntTerm(size);
-  if(!YAP_Unify(YAP_Deref(YAP_ARG2),t_size) )   
+  if(!YAP_Unify(YAP_ARG2,t_size) )   
     return (FALSE);
   
   return(TRUE);
@@ -207,6 +207,8 @@ p_rl_set_in(void) {
 #endif
   return (TRUE);
 }
+
+#ifdef UNUSED
  /*
  *
  *
@@ -234,6 +236,8 @@ p_rl_in(void) {
     return (TRUE);
   return (FALSE);
 }
+#endif
+
 /*
  *
  *
@@ -372,7 +376,6 @@ int
 p_rl_b_in2(void) {
 
   YAP_Term t1=YAP_Deref(YAP_ARG1);
-  YAP_Term t2=YAP_Deref(YAP_ARG2);
   IDTYPE id;
   NUM val;
   RL_Tree *tree;
@@ -422,7 +425,7 @@ p_rl_b_in1(void) {
   }
 }
 /* ******************************************************* */
-void init_rl(){
+void init_rl(void){
 
      
  YAP_UserCPredicate("rl_new", p_rl_new,2);        //  Maximum -> RangeID
diff --git a/pl/boot.yap b/pl/boot.yap
index 8671058d4..9d6d8e7a0 100644
--- a/pl/boot.yap
+++ b/pl/boot.yap
@@ -165,13 +165,13 @@ true :- true.
 	prompt(_,'   ?- '),
 	prompt('   | '),
 	'$run_toplevel_hooks',
-	'$read_vars'(user_input,Command,_,_,Varnames),
+	'$read_vars'(user_input,Command,_,Pos,Varnames),
 	nb_setval('$spy_gn',1),
 		% stop at spy-points if debugging is on.
 	nb_setval('$debug_run',off),
 	nb_setval('$debug_zip',off),
 	prompt(_,'   |: '),
-	'$command'((?-Command),Varnames,top),
+	'$command'((?-Command),Varnames,Pos,top),
 	'$sync_mmapped_arrays',
 	set_value('$live','$false').
 
@@ -283,16 +283,16 @@ true :- true.
 	recordz('$corout','$corout'(main,main,'$corout'([],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[])),_Ref),
 	recorda('$result',going,_).
 
-'$command'(C,VL,Con) :-
+'$command'(C,VL,Pos,Con) :-
 	'$access_yap_flags'(9,1), !,
-	 '$execute_command'(C,VL,Con,C).
-'$command'(C,VL,Con) :-
+	 '$execute_command'(C,VL,Pos,Con,C).
+'$command'(C,VL,Pos,Con) :-
 	( (Con = top ; var(C) ; C = [_|_])  ->  
-	  '$execute_command'(C,VL,Con,C), ! ;
+	  '$execute_command'(C,VL,Pos,Con,C), ! ;
 	  % do term expansion
 	  expand_term(C, EC),
 	  % execute a list of commands
-	  '$execute_commands'(EC,VL,Con,C),
+	  '$execute_commands'(EC,VL,Pos,Con,C),
 	  % succeed only if the *original* was at end of file.
 	  C == end_of_file
 	).
@@ -300,18 +300,18 @@ true :- true.
  %
  % Hack in case expand_term has created a list of commands.
  %
- '$execute_commands'(V,_,_,Source) :- var(V), !,
+ '$execute_commands'(V,_,_,_,Source) :- var(V), !,
 	 '$do_error'(instantiation_error,meta_call(Source)).
- '$execute_commands'([],_,_,_) :- !.
- '$execute_commands'([C|Cs],VL,Con,Source) :- !,
+ '$execute_commands'([],_,_,_,_) :- !.
+ '$execute_commands'([C|Cs],VL,Pos,Con,Source) :- !,
 	 (
-	   '$execute_command'(C,VL,Con,Source),
+	   '$execute_command'(C,VL,Pos,Con,Source),
 	   fail	
 	 ;
-	   '$execute_commands'(Cs,VL,Con,Source)
+	   '$execute_commands'(Cs,VL,Pos,Con,Source)
 	 ).
- '$execute_commands'(C,VL,Con,Source) :-
-	 '$execute_command'(C,VL,Con,Source).
+ '$execute_commands'(C,VL,Pos,Con,Source) :-
+	 '$execute_command'(C,VL,Pos,Con,Source).
 
 
 
@@ -319,27 +319,27 @@ true :- true.
  %
  %
 
- '$execute_command'(C,_,top,Source) :- var(C), !,
+ '$execute_command'(C,_,_,top,Source) :- var(C), !,
 	 '$do_error'(instantiation_error,meta_call(Source)).
- '$execute_command'(C,_,top,Source) :- number(C), !,
+ '$execute_command'(C,_,_,top,Source) :- number(C), !,
 	 '$do_error'(type_error(callable,C),meta_call(Source)).
- '$execute_command'(R,_,top,Source) :- db_reference(R), !,
+ '$execute_command'(R,_,_,top,Source) :- db_reference(R), !,
 	 '$do_error'(type_error(callable,R),meta_call(Source)).
- '$execute_command'(end_of_file,_,_,_) :- !.
- '$execute_command'(Command,_,_,_) :-
+ '$execute_command'(end_of_file,_,_,_,_) :- !.
+ '$execute_command'(Command,_,_,_,_) :-
 	 nb_getval('$if_skip_mode',skip),
 	 \+ '$if_directive'(Command),
 	 !.
- '$execute_command'((:-G),_,Option,_) :- !,
+ '$execute_command'((:-G),_,_,Option,_) :- !,
 	 '$current_module'(M),
 	 % allow user expansion
 	 expand_term((:- G), O),
          O = (:- G1),
 	 '$process_directive'(G1, Option, M).
- '$execute_command'((?-G),V,_,Source) :- !,
-	 '$execute_command'(G,V,top,Source).
- '$execute_command'(G,V,Option,Source) :-
-	 '$continue_with_command'(Option,V,G,Source).
+ '$execute_command'((?-G),V,Pos,_,Source) :- !,
+	 '$execute_command'(G,V,Pos,top,Source).
+ '$execute_command'(G,V,Pos,Option,Source) :-
+	 '$continue_with_command'(Option,V,Pos,G,Source).
 
  %
  % This command is very different depending on the language mode we are in.
@@ -377,34 +377,34 @@ true :- true.
  '$process_directive'(G, _, M) :-
 	 ( '$do_yes_no'(G,M) -> true ; format(user_error,':- ~w:~w failed.~n',[M,G]) ).
 
- '$continue_with_command'(reconsult,V,G,Source) :-
-	 '$go_compile_clause'(G,V,5,Source),
+ '$continue_with_command'(reconsult,V,Pos,G,Source) :-
+	 '$go_compile_clause'(G,V,Pos,5,Source),
 	 fail.
- '$continue_with_command'(consult,V,G,Source) :-
-	 '$go_compile_clause'(G,V,13,Source),
+ '$continue_with_command'(consult,V,Pos,G,Source) :-
+	 '$go_compile_clause'(G,V,Pos,13,Source),
 	 fail.
- '$continue_with_command'(top,V,G,_) :-
+ '$continue_with_command'(top,V,_,G,_) :-
 	 '$query'(G,V).
 
  %
  % not 100% compatible with SICStus Prolog, as SICStus Prolog would put
  % module prefixes all over the place, although unnecessarily so.
  %
- '$go_compile_clause'(G,V,N,Source) :-
+ '$go_compile_clause'(G,V,Pos,N,Source) :-
 	 '$current_module'(Mod),
-	 '$go_compile_clause'(G,V,N,Mod,Mod,Source).
+	 '$go_compile_clause'(G,V,Pos,N,Mod,Mod,Source).
  
-'$go_compile_clause'(M:G,V,N,_,_,Source) :- !,
-	  '$go_compile_clause'(G,V,N,M,M,Source).
-'$go_compile_clause'((M:H :- B),V,N,_,BodyMod,Source) :- !,
-	  '$go_compile_clause'((H :- B),V,N,M,BodyMod,Source).
-'$go_compile_clause'(G,V,N,HeadMod,BodyMod,Source) :- !,
-	 '$prepare_term'(G, V, G0, G1, BodyMod, HeadMod, Source),
+'$go_compile_clause'(M:G,V,Pos,N,_,_,Source) :- !,
+	  '$go_compile_clause'(G,V,Pos,N,M,M,Source).
+'$go_compile_clause'((M:H :- B),V,Pos,N,_,BodyMod,Source) :- !,
+	  '$go_compile_clause'((H :- B),V,Pos,N,M,BodyMod,Source).
+'$go_compile_clause'(G,V,Pos,N,HeadMod,BodyMod,Source) :- !,
+	 '$prepare_term'(G, V, Pos, G0, G1, BodyMod, HeadMod, Source),
 	 '$$compile'(G1, G0, N, HeadMod).
 
- '$prepare_term'(G, V, G0, G1, BodyMod, SourceMod, Source) :-
+ '$prepare_term'(G, V, Pos, G0, G1, BodyMod, SourceMod, Source) :-
 	 ( get_value('$syntaxcheckflag',on) ->
-		 '$check_term'(Source, V, BodyMod) ; true ),
+		 '$check_term'(Source, V, Pos, BodyMod) ; true ),
 	 '$precompile_term'(G, G0, G1, BodyMod, SourceMod).
 
  % process an input clause
@@ -1006,8 +1006,8 @@ bootstrap(F) :-
 	!.
 
 '$enter_command'(Stream,Status) :-
-	'$read_vars'(Stream,Command,_,_,Vars),
-	'$command'(Command,Vars,Status).
+	'$read_vars'(Stream,Command,_,Pos,Vars),
+	'$command'(Command,Vars,Pos,Status).
 
 '$abort_loop'(Stream) :-
 	'$do_error'(permission_error(input,closed_stream,Stream), loop).
diff --git a/pl/checker.yap b/pl/checker.yap
index 86bd926be..f37c6ced4 100644
--- a/pl/checker.yap
+++ b/pl/checker.yap
@@ -120,20 +120,20 @@ no_style_check([H|T]) :- no_style_check(H), no_style_check(T).
 	'$values'('$syntaxcheckmultiple',O,N).
 
 
-'$check_term'(T,_,M) :-
+'$check_term'(T,_,P,M) :-
 	get_value('$syntaxcheckdiscontiguous',on),
 	'$xtract_head'(T,M,NM,_,F,A),
 	'$handle_discontiguous'(F,A,NM), fail.
-'$check_term'(T,_,M) :-
+'$check_term'(T,_,P,M) :-
 	get_value('$syntaxcheckmultiple',on),
 	'$xtract_head'(T,M,NM,_,F,A),
 	'$handle_multiple'(F,A,NM), fail.
-'$check_term'(T,VL,_) :-
+'$check_term'(T,VL,P,_) :-
 	get_value('$syntaxchecksinglevar',on),
 	( '$chk_binding_vars'(T),
 	  '$sv_list'(VL,Sv) ->
 	  '$sv_warning'(Sv,T) ), fail.
-'$check_term'(_,_,_).
+'$check_term'(_,_,_,_).
 
 '$chk_binding_vars'(V) :- var(V), !, V = '$V'(_).
 '$chk_binding_vars'('$V'(off)) :- !.
diff --git a/pl/hacks.yap b/pl/hacks.yap
index 5a277919c..dbc4dec49 100644
--- a/pl/hacks.yap
+++ b/pl/hacks.yap
@@ -151,14 +151,14 @@ beautify_hidden_goal('$csult'(Files,Mod),prolog) -->
 	[reconsult(Mod:Files)].
 beautify_hidden_goal('$use_module'(Files,Mod,Is),prolog) -->
 	[use_module(Mod,Files,Is)].
-beautify_hidden_goal('$continue_with_command'(reconsult,V,G,Source),prolog) -->
-	['Assert'(G,V,Source)].
-beautify_hidden_goal('$continue_with_command'(consult,V,G,Source),prolog) -->
-	['Assert'(G,V,Source)].
-beautify_hidden_goal('$continue_with_command'(top,V,G,_),prolog) -->
-	['Query'(G,V)].
-beautify_hidden_goal('$continue_with_command'(Command,V,G,Source),prolog) -->
-	['TopLevel'(Command,G,V,Source)].
+beautify_hidden_goal('$continue_with_command'(reconsult,V,P,G,Source),prolog) -->
+	['Assert'(G,V,P,Source)].
+beautify_hidden_goal('$continue_with_command'(consult,V,P,G,Source),prolog) -->
+	['Assert'(G,V,P,Source)].
+beautify_hidden_goal('$continue_with_command'(top,V,P,G,_),prolog) -->
+	['Query'(G,V,P)].
+beautify_hidden_goal('$continue_with_command'(Command,V,P,G,Source),prolog) -->
+	['TopLevel'(Command,G,V,P,Source)].
 beautify_hidden_goal('$spycall'(G,M,InControl,Redo),prolog) -->
 	['DebuggerCall'(M:G, InControl, Redo)].
 beautify_hidden_goal('$do_spy'(Goal, Mod, CP, InControl),prolog) -->
@@ -167,8 +167,8 @@ beautify_hidden_goal('$system_catch'(G,Mod,Exc,Handler),prolog) -->
 	[catch(Mod:G, Exc, Handler)].
 beautify_hidden_goal('$catch'(G,Exc,Handler),prolog) -->
 	[catch(G, Exc, Handler)].
-beautify_hidden_goal('$execute_command'(Query,V,Option,Source),prolog) -->
-	[toplevel_query(Query, V, Option, Source)].
+beautify_hidden_goal('$execute_command'(Query,V,P,Option,Source),prolog) -->
+	[toplevel_query(Query, V, P, Option, Source)].
 beautify_hidden_goal('$process_directive'(Gs,_,Mod),prolog) -->
 	[(:- Mod:Gs)].
 beautify_hidden_goal('$loop'(Stream,Option),prolog) -->
diff --git a/pl/messages.yap b/pl/messages.yap
index 350e1d462..858a664ae 100644
--- a/pl/messages.yap
+++ b/pl/messages.yap
@@ -31,9 +31,9 @@ file_location(Prefix) -->
 	[ nl ].
 
 file_position(user_input,LN,MsgCodes) -->
-	[ '~a at user_input near line ~d.' - [MsgCodes,LN] ].
+	[ '~a (user_input:~d).' - [MsgCodes,LN] ].
 file_position(FileName,LN,MsgCodes) -->
-	[ '~a at file ~a, near line ~d.' - [MsgCodes,FileName,LN] ].
+	[ '~a (~a:~d).' - [MsgCodes,FileName,LN] ].
 
 generate_message(halt) --> !,
 	['YAP execution halted'].