diff --git a/C/atomic.c b/C/atomic.c
index 26c331754..fdc89aefa 100755
--- a/C/atomic.c
+++ b/C/atomic.c
@@ -700,7 +700,7 @@ restart_aux:
   if (IsNumTerm(t1)) {
     Term t2 = Deref(ARG2);
     Term t12 = Yap_NumberToListOfAtoms(t1 PASS_REGS);
-    if (t12) {
+    if (t12 && t2) {
       {
         pop_text_stack(l);
         return Yap_unify(t12, t2);
diff --git a/C/errors.c b/C/errors.c
index 40caa5fef..74dc66329 100755
--- a/C/errors.c
+++ b/C/errors.c
@@ -786,12 +786,14 @@ yamop *Yap_Error__(bool throw, const char *file, const char *function,
     fprintf(stderr, "***** Processing Error %d (%x) %s***\n", type,
             LOCAL_PrologMode, fmt);
 #endif
-if (LOCAL_ActiveError->errorNo == SYNTAX_ERROR) {
-  ;
-LOCAL_ActiveError->errorClass = SYNTAX_ERROR_CLASS;
-  return P;
-}
-if (type == INTERRUPT_EVENT) {
+  if (LOCAL_ActiveError->errorNo == SYNTAX_ERROR) {
+    LOCAL_ActiveError->errorClass = SYNTAX_ERROR_CLASS;
+    return P;
+  } else if (LOCAL_ActiveError->errorNo == SYNTAX_ERROR_NUMBER) {
+    LOCAL_ActiveError->errorClass = SYNTAX_ERROR_CLASS;
+    LOCAL_ActiveError->errorNo = SYNTAX_ERROR;
+  }
+  if (type == INTERRUPT_EVENT) {
     fprintf(stderr, "%% YAP exiting: cannot handle signal %d\n",
             (int)IntOfTerm(where));
     Yap_exit(1);
diff --git a/C/exec.c b/C/exec.c
index 00ab8ddda..0500d6857 100755
--- a/C/exec.c
+++ b/C/exec.c
@@ -1233,8 +1233,15 @@ static Int creep_step(USES_REGS1) { /* '$execute_nonstop'(Goal,Mod)
   return rc;
 }
 
-static Int execute_nonstop(USES_REGS1) { /* '$execute_nonstop'(Goal,Mod)
-                                          */
+
+/**
+ * @brief Two argument version of non-interruptible execution: this will
+ * ignore signals including debugging requests.
+ * 
+ * @return Int succeeds if it can transfer control.
+ */
+
+static Int execute_nonstop(USES_REGS1) { 
   Term t = Deref(ARG1);
   Term mod = Deref(ARG2);
   unsigned int arity;
@@ -1309,6 +1316,20 @@ static Int execute_nonstop(USES_REGS1) { /* '$execute_nonstop'(Goal,Mod)
   }
 }
 
+
+/**
+ * @brief One argument version of non-interruptible execution: this will
+ * ignore signals including debugging requests.
+ * 
+ * @return Int succeeds if it can transfer control.
+ */
+static Int execute_nonstop1(USES_REGS1)
+{
+ ARG2 = CurrentModule;
+return execute_nonstop( PASS_REGS1 );
+}
+
+
 static Int execute_0(USES_REGS1) { /* '$execute_0'(Goal)	 */
   Term mod = CurrentModule;
   Term t = Yap_YapStripModule(Deref(ARG1), &mod);
@@ -2233,6 +2254,7 @@ void Yap_InitExecFs(void) {
 #endif
   Yap_InitCPred("$execute0", 2, execute0, NoTracePredFlag);
   Yap_InitCPred("$execute_nonstop", 2, execute_nonstop, NoTracePredFlag);
+  Yap_InitCPred("$execute_nonstop", 1, execute_nonstop1, NoTracePredFlag);
   Yap_InitCPred("$creep_step", 2, creep_step, NoTracePredFlag);
   Yap_InitCPred("$execute_clause", 4, execute_clause, NoTracePredFlag);
   Yap_InitCPred("$current_choice_point", 1, current_choice_point, 0);
diff --git a/C/text.c b/C/text.c
index 627efd46a..47d442169 100644
--- a/C/text.c
+++ b/C/text.c
@@ -249,42 +249,62 @@ static void *codes2buf(Term t0, void *b0, bool *get_codes USES_REGS) {
     while (IsPairTerm(t)) {
       Term hd = HeadOfTerm(t);
       if (IsVarTerm(hd)) {
-        Yap_Error(INSTANTIATION_ERROR, t0, "scanning list of codes");
+        Yap_ThrowError(INSTANTIATION_ERROR, hd, "scanning list of codes");
         return NULL;
       }
       if (!IsIntegerTerm(hd)) {
-        Yap_Error(TYPE_ERROR_INTEGER, t0, "scanning list of codes");
+        Yap_ThrowError(TYPE_ERROR_CHARACTER_CODE, hd, "scanning list of codes");
         return NULL;
       }
       Int code = IntegerOfTerm(hd);
       if (code < 0) {
-        Yap_Error(REPRESENTATION_ERROR_CHARACTER_CODE, t0,
+        Yap_ThrowError(TYPE_ERROR_CHARACTER_CODE, hd,
                   "scanning list of codes");
         return NULL;
       }
       length += put_utf8(ar, code);
       t = TailOfTerm(t);
+      if (IsVarTerm(t)) {
+        Yap_ThrowError(INSTANTIATION_ERROR, t, "scanning list of codes");
+        return NULL;
+      }
+      if (!IsPairTerm(t) && t != TermNil) {
+        Yap_ThrowError(TYPE_ERROR_LIST, t, "scanning list of codes");
+        return NULL;
+      }
     }
   } else {
     while (IsPairTerm(t)) {
       Term hd = HeadOfTerm(t);
+      if (IsVarTerm(hd)) {
+        Yap_ThrowError(INSTANTIATION_ERROR, hd, "scanning list of codes");
+        return NULL;
+      }
       if (!IsAtomTerm(hd)) {
-        Yap_Error(TYPE_ERROR_ATOM, t0, "scanning list of atoms");
+        Yap_ThrowError(TYPE_ERROR_CHARACTER, hd, "scanning list of atoms");
         return NULL;
       }
       const char *code = RepAtom(AtomOfTerm(hd))->StrOfAE;
       if (code < 0) {
-        Yap_Error(REPRESENTATION_ERROR_CHARACTER, t0, "scanning list of atoms");
+        Yap_ThrowError(TYPE_ERROR_CHARACTER, hd, "scanning list of atoms");
         return NULL;
       }
       length += strlen(code);
       t = TailOfTerm(t);
+      if (IsVarTerm(t)) {
+        Yap_ThrowError(INSTANTIATION_ERROR, t, "scanning list of codes");
+        return NULL;
+      }
+      if (!IsPairTerm(t) && t != TermNil) {
+        Yap_ThrowError(TYPE_ERROR_LIST, t, "scanning list of codes");
+        return NULL;
+      }
     }
   }
 
   if (!IsVarTerm(t)) {
     if (t != TermNil) {
-      Yap_Error(TYPE_ERROR_INTEGER, t0, "scanning list of codes");
+      Yap_ThrowError(TYPE_ERROR_LIST, t0, "scanning list of codes");
       return NULL;
     }
   }
@@ -294,7 +314,6 @@ static void *codes2buf(Term t0, void *b0, bool *get_codes USES_REGS) {
   if (codes) {
     while (IsPairTerm(t)) {
       Term hd = HeadOfTerm(t);
-
       Int code = IntegerOfTerm(hd);
 
       st = st + put_utf8(st, code);
@@ -736,7 +755,18 @@ static size_t write_length(const unsigned char *s0, seq_tv_t *out USES_REGS) {
 static Term write_number(unsigned char *s, seq_tv_t *out,
                          bool error_on USES_REGS) {
   Term t;
-  t = Yap_StringToNumberTerm((char *)s, &out->enc,true);
+  yap_error_descriptor_t new_error;
+  bool mdnew = true;
+  Yap_pushErrorContext(error_on, &new_error);
+  t = Yap_StringToNumberTerm((char *)s, &out->enc,error_on);
+    Yap_popErrorContext(mdnew, true);
+  if (error_on) {
+    if (t == 0 && LOCAL_ActiveError->errorNo != YAP_NO_ERROR) {
+      P = FAILCODE;
+      Yap_HandleError("scanningx");
+    }
+  }
+  Yap_ResetException(LOCAL_ActiveError);
   return t;
 }
 
diff --git a/H/YapFlags.h b/H/YapFlags.h
index aaff6428f..88e6ddab3 100644
--- a/H/YapFlags.h
+++ b/H/YapFlags.h
@@ -17,7 +17,7 @@
 
 /** @file YapFlags.h
 
-    @addtogroup Flags
+    @addtogroup YAPFlags
 */
 
 #ifndef YAP_FLAGS_H
diff --git a/H/YapLFlagInfo.h b/H/YapLFlagInfo.h
index 7acb70172..da6bcda8b 100644
--- a/H/YapLFlagInfo.h
+++ b/H/YapLFlagInfo.h
@@ -18,10 +18,12 @@
 
 /** @file YapLFlagInfo.h
 
-    @addtogroup Flags
+    @addtogroup YAPFlags
 */
 
+/** + `autoload`: set the system to look for undefined procedures */
 YAP_FLAG(  AUTOLOAD_FLAG, "autoload", true, booleanFlag, "false" , NULL ),
+/** + `read-only flag, that tells if Prolog is in an inner top-level */
 YAP_FLAG(  BREAK_LEVEL_FLAG, "break_level", true, nat, "0" , NULL ),
 YAP_FLAG(  CALL_COUNTING_FLAG, "call_counting", true, booleanFlag, "true" , NULL ), /** + `call_counting`
 
diff --git a/docs/CMakeLists.txt b/docs/CMakeLists.txt
index 765680d56..17c5c8012 100644
--- a/docs/CMakeLists.txt
+++ b/docs/CMakeLists.txt
@@ -33,6 +33,8 @@ SET (CMAKE_HTML_EXTRA_
     endforeach(i ${CMAKE_HTML_EXTRA_})
 
 set(DOCS_EXCLUDE_
+${CMAKE_SOURCE_DIR}/build
+${CMAKE_SOURCE_DIR}/Debug
 ${CMAKE_SOURCE_DIR}/packages/jpl
 ${CMAKE_SOURCE_DIR}/packages/swig
 ${CMAKE_SOURCE_DIR}/packages/myddas/sqlite3/src
@@ -47,7 +49,6 @@ ${CMAKE_SOURCE_DIR}/packages/gecode/3.7.0
 ${CMAKE_SOURCE_DIR}/packages/gecode/3.6.0
 ${CMAKE_SOURCE_DIR}/packages/gecode/dev
 ${CMAKE_SOURCE_DIR}/C/traced_absmi_insts.h
-${CMAKE_SOURCE_DIR}/H/locals.h
 ${CMAKE_SOURCE_DIR}/H/globals.h
 ${CMAKE_SOURCE_DIR}/packages/cplint
 ${CMAKE_SOURCE_DIR}/packages/CLPBN/examples
diff --git a/docs/Doxyfile b/docs/Doxyfile
index 35b3be2dc..b06c8b843 100644
--- a/docs/Doxyfile
+++ b/docs/Doxyfile
@@ -816,7 +816,7 @@ RECURSIVE              = YES
 # Note that relative paths are relative to the directory from which doxygen is
 # run.
 
-EXCLUDE                = /home/vsc/github/yap-6.3/packages/jpl /home/vsc/github/yap-6.3/packages/swig /home/vsc/github/yap-6.3/packages/myddas/sqlite3/src /home/vsc/github/yap-6.3/packages/gecode/4.4.0 /home/vsc/github/yap-6.3/packages/gecode/4.2.1 /home/vsc/github/yap-6.3/packages/gecode/4.2.0 /home/vsc/github/yap-6.3/packages/gecode/4.0.0 /home/vsc/github/yap-6.3/packages/gecode/3.7.3 /home/vsc/github/yap-6.3/packages/gecode/3.7.2 /home/vsc/github/yap-6.3/packages/gecode/3.7.1 /home/vsc/github/yap-6.3/packages/gecode/3.7.0 /home/vsc/github/yap-6.3/packages/gecode/3.6.0 /home/vsc/github/yap-6.3/packages/gecode/dev /home/vsc/github/yap-6.3/C/traced_absmi_insts.h /home/vsc/github/yap-6.3/H/locals.h /home/vsc/github/yap-6.3/H/globals.h /home/vsc/github/yap-6.3/packages/cplint /home/vsc/github/yap-6.3/packages/CLPBN/examples /home/vsc/github/yap-6.3/packages/CLPBN/horus /home/vsc/github/yap-6.3/packages/prosqlite /home/vsc/github/yap-6.3/packages/pyswip /home/vsc/github/yap-6.3/packages/yap-lbfgs/liblbfgs-1.10 /home/vsc/github/yap-6.3/library/dialect/swi/os /home/vsc/github/yap-6.3/packages/gecode/gecode3_yap.cc /home/vsc/github/yap-6.3/packages/gecode/gecode4_yap.cc /home/vsc/github/yap-6.3/packages/gecode/gecode3.yap /home/vsc/github/yap-6.3/packages/gecode/gecode4.yap /home/vsc/github/yap-6.3/packages/gecode/gecode3_yap_hand_written.yap /home/vsc/github/yap-6.3/packages/gecode/gecode4_yap_hand_written.yap */CMakeFiles/* *~ */ 
+EXCLUDE                = /home/vsc/github/yap-6.3/build /home/vsc/github/yap-6.3/Debug /home/vsc/github/yap-6.3/packages/jpl /home/vsc/github/yap-6.3/packages/swig /home/vsc/github/yap-6.3/packages/myddas/sqlite3/src /home/vsc/github/yap-6.3/packages/gecode/4.4.0 /home/vsc/github/yap-6.3/packages/gecode/4.2.1 /home/vsc/github/yap-6.3/packages/gecode/4.2.0 /home/vsc/github/yap-6.3/packages/gecode/4.0.0 /home/vsc/github/yap-6.3/packages/gecode/3.7.3 /home/vsc/github/yap-6.3/packages/gecode/3.7.2 /home/vsc/github/yap-6.3/packages/gecode/3.7.1 /home/vsc/github/yap-6.3/packages/gecode/3.7.0 /home/vsc/github/yap-6.3/packages/gecode/3.6.0 /home/vsc/github/yap-6.3/packages/gecode/dev /home/vsc/github/yap-6.3/C/traced_absmi_insts.h /home/vsc/github/yap-6.3/H/globals.h /home/vsc/github/yap-6.3/packages/cplint /home/vsc/github/yap-6.3/packages/CLPBN/examples /home/vsc/github/yap-6.3/packages/CLPBN/horus /home/vsc/github/yap-6.3/packages/prosqlite /home/vsc/github/yap-6.3/packages/pyswip /home/vsc/github/yap-6.3/packages/yap-lbfgs/liblbfgs-1.10 /home/vsc/github/yap-6.3/library/dialect/swi/os /home/vsc/github/yap-6.3/packages/gecode/gecode3_yap.cc /home/vsc/github/yap-6.3/packages/gecode/gecode4_yap.cc /home/vsc/github/yap-6.3/packages/gecode/gecode3.yap /home/vsc/github/yap-6.3/packages/gecode/gecode4.yap /home/vsc/github/yap-6.3/packages/gecode/gecode3_yap_hand_written.yap /home/vsc/github/yap-6.3/packages/gecode/gecode4_yap_hand_written.yap */CMakeFiles/* *~ */ 
 
 # The EXCLUDE_SYMLINKS tag can be used to select whether or not files or
 # directories that are symbolic links (a Unix file system feature) are excluded
diff --git a/docs/checkpl.yap b/docs/checkpl.yap
new file mode 100644
index 000000000..a07a1aa5d
--- /dev/null
+++ b/docs/checkpl.yap
@@ -0,0 +1,65 @@
+
+:- use_module(library(lists)).
+:- use_module(library(lineutils)).
+
+:- initialization(main).
+
+main :-
+  %system('find . \( -name '*.pl' -o -name '*.yap'  -o -name '*.c' -o -name '*.h' -o -name '*.cpp' -o -name '*.hh' \) -type f -print | xargs grep  '@defgroup\|@ingroup\|@addtogroup\|@{|@}').
+
+ file_filter_with_start_end( docs, tmp, add2graph, initgraph,  checkgraph).
+
+initgraph(_,_).
+
+:- dynamic node/3, edge/3, e_b_n/3.
+
+checkgraph(_,_) :-
+  e_b_n(F,KN,_C),
+  node(KF,KN,_),
+  add_edge(KF, F, KN),
+  fail.
+checkgraph(_,_) :-
+  listing(node),
+  listing(edge).
+
+
+ add2graph(Line, _Out) :-
+    split( Line, "% \t/*:", [File, Job, Name|_]),
+    append(   _, L, Line),
+    append(Name, R, L),
+    dispatch( Name, File, Job, R).
+
+dispatch( Name, File, "defgroup", Comment):-
+    atom_codes(KN, Name),
+    atom_codes(KF, File),
+    atom_codes(C, Comment),
+          add_node(KF, KN,C).
+dispatch( Name, File, "addtogroup", Comment):-
+  atom_codes(KN, Name),
+  atom_codes(KF, File),
+  atom_codes(C, Comment),
+  add_node_edge(KF, KN,C).
+dispatch( Name, File, "ingroup", Comment):-
+    atom_codes(KN, Name),
+    atom_codes(KF, File),
+    atom_codes(C, Comment),
+          add_edge(KF, KN,C).
+add_node(F, K,_C) :-
+  node(_,K,_),
+  throw( repeat(F:K) ).
+add_node(F, K,C) :-
+  assert(node(F,K,C)).
+
+  add_node_edge(F, K,_C) :-
+    node(F1,K,_),
+    !,
+    assert(edge(F1,F,K)).
+  add_node_edge(F, K,C) :-
+    assert(node(F,K,C)).
+
+    add_edge(F, K,_C) :-
+      node(F1,K,_),
+      !,
+      assert(edge(F1,F,K)).
+    add_edge(F, K,C) :-
+      assert(e_b_n(F,K,C)).
diff --git a/docs/md/yap.md b/docs/md/yap.md
index 894b0a0bb..b2aeb8d43 100644
--- a/docs/md/yap.md
+++ b/docs/md/yap.md
@@ -17,7 +17,7 @@ Porto.
 The manual is organised as follows:
 
 
-+ @subpage  install
++ @subpage  INSTALL
 
 + @subpage run
 
diff --git a/docs/my.yap b/docs/my.xxx
similarity index 100%
rename from docs/my.yap
rename to docs/my.xxx
diff --git a/docs/yapdocs.yap b/docs/yapdocs.xxx
similarity index 100%
rename from docs/yapdocs.yap
rename to docs/yapdocs.xxx
diff --git a/include/YapErrors.h b/include/YapErrors.h
index 303f564e1..f2cdf62a2 100644
--- a/include/YapErrors.h
+++ b/include/YapErrors.h
@@ -141,6 +141,7 @@ E(RESOURCE_ERROR_TRAIL, RESOURCE_ERROR, "trail_space")
 E(RESOURCE_ERROR_STACK, RESOURCE_ERROR, "stack_space")
 
 E1(SYNTAX_ERROR, SYNTAX_ERROR_CLASS, "syntax_error")
+E1(SYNTAX_ERROR_NUMBER, SYNTAX_ERROR_CLASS, "syntax_error")
 
 E(SYSTEM_ERROR_INTERNAL, SYSTEM_ERROR_CLASS, "internal")
 E(SYSTEM_ERROR_COMPILER, SYSTEM_ERROR_CLASS, "compiler")
diff --git a/os/chartypes.c b/os/chartypes.c
index 67d407a88..b85c6a7cd 100644
--- a/os/chartypes.c
+++ b/os/chartypes.c
@@ -82,8 +82,7 @@ Term Yap_StringToNumberTerm(const char *s, encoding_t *encp, bool error_on) {
   CACHE_REGS
   int sno;
   Term t;
-  yap_error_descriptor_t new_error;
-    int i = push_text_stack();
+  int i = push_text_stack();
 
   sno = Yap_open_buf_read_stream(s, strlen(s), encp, MEM_BUF_USER);
   if (sno < 0)
@@ -92,7 +91,6 @@ Term Yap_StringToNumberTerm(const char *s, encoding_t *encp, bool error_on) {
     GLOBAL_Stream[sno].encoding = *encp;
   else
     GLOBAL_Stream[sno].encoding = LOCAL_encoding;
-    bool new_rec = Yap_pushErrorContext(error_on,&new_error);
 #ifdef __ANDROID__
   while (*s && isblank(*s) && Yap_wide_chtype(*s) == BS)
     s++;
@@ -101,7 +99,6 @@ Term Yap_StringToNumberTerm(const char *s, encoding_t *encp, bool error_on) {
     Yap_CloseStream(sno);
   UNLOCK(GLOBAL_Stream[sno].streamlock);
     pop_text_stack(i);
-    Yap_popErrorContext(new_rec , error_on);
   return t;
 }
 
diff --git a/packages/raptor/doc/Doxyfile b/packages/raptor/doc/Doxyfile
index 651e67e6e..140da6681 100644
--- a/packages/raptor/doc/Doxyfile
+++ b/packages/raptor/doc/Doxyfile
@@ -816,7 +816,7 @@ RECURSIVE              = YES
 # Note that relative paths are relative to the directory from which doxygen is
 # run.
 
-EXCLUDE                = /home/vsc/github/yap-6.3/packages/jpl /home/vsc/github/yap-6.3/packages/swig /home/vsc/github/yap-6.3/packages/myddas/sqlite3/src /home/vsc/github/yap-6.3/packages/gecode/4.4.0 /home/vsc/github/yap-6.3/packages/gecode/4.2.1 /home/vsc/github/yap-6.3/packages/gecode/4.2.0 /home/vsc/github/yap-6.3/packages/gecode/4.0.0 /home/vsc/github/yap-6.3/packages/gecode/3.7.3 /home/vsc/github/yap-6.3/packages/gecode/3.7.2 /home/vsc/github/yap-6.3/packages/gecode/3.7.1 /home/vsc/github/yap-6.3/packages/gecode/3.7.0 /home/vsc/github/yap-6.3/packages/gecode/3.6.0 /home/vsc/github/yap-6.3/packages/gecode/dev /home/vsc/github/yap-6.3/C/traced_absmi_insts.h /home/vsc/github/yap-6.3/H/locals.h /home/vsc/github/yap-6.3/H/globals.h /home/vsc/github/yap-6.3/packages/cplint /home/vsc/github/yap-6.3/packages/CLPBN/examples /home/vsc/github/yap-6.3/packages/CLPBN/horus /home/vsc/github/yap-6.3/packages/prosqlite /home/vsc/github/yap-6.3/packages/pyswip /home/vsc/github/yap-6.3/packages/yap-lbfgs/liblbfgs-1.10 /home/vsc/github/yap-6.3/library/dialect/swi/os /home/vsc/github/yap-6.3/packages/gecode/gecode3_yap.cc /home/vsc/github/yap-6.3/packages/gecode/gecode4_yap.cc /home/vsc/github/yap-6.3/packages/gecode/gecode3.yap /home/vsc/github/yap-6.3/packages/gecode/gecode4.yap /home/vsc/github/yap-6.3/packages/gecode/gecode3_yap_hand_written.yap /home/vsc/github/yap-6.3/packages/gecode/gecode4_yap_hand_written.yap */CMakeFiles/* *~ */ 
+EXCLUDE                = /home/vsc/github/yap-6.3/build /home/vsc/github/yap-6.3/Debug /home/vsc/github/yap-6.3/packages/jpl /home/vsc/github/yap-6.3/packages/swig /home/vsc/github/yap-6.3/packages/myddas/sqlite3/src /home/vsc/github/yap-6.3/packages/gecode/4.4.0 /home/vsc/github/yap-6.3/packages/gecode/4.2.1 /home/vsc/github/yap-6.3/packages/gecode/4.2.0 /home/vsc/github/yap-6.3/packages/gecode/4.0.0 /home/vsc/github/yap-6.3/packages/gecode/3.7.3 /home/vsc/github/yap-6.3/packages/gecode/3.7.2 /home/vsc/github/yap-6.3/packages/gecode/3.7.1 /home/vsc/github/yap-6.3/packages/gecode/3.7.0 /home/vsc/github/yap-6.3/packages/gecode/3.6.0 /home/vsc/github/yap-6.3/packages/gecode/dev /home/vsc/github/yap-6.3/C/traced_absmi_insts.h /home/vsc/github/yap-6.3/H/globals.h /home/vsc/github/yap-6.3/packages/cplint /home/vsc/github/yap-6.3/packages/CLPBN/examples /home/vsc/github/yap-6.3/packages/CLPBN/horus /home/vsc/github/yap-6.3/packages/prosqlite /home/vsc/github/yap-6.3/packages/pyswip /home/vsc/github/yap-6.3/packages/yap-lbfgs/liblbfgs-1.10 /home/vsc/github/yap-6.3/library/dialect/swi/os /home/vsc/github/yap-6.3/packages/gecode/gecode3_yap.cc /home/vsc/github/yap-6.3/packages/gecode/gecode4_yap.cc /home/vsc/github/yap-6.3/packages/gecode/gecode3.yap /home/vsc/github/yap-6.3/packages/gecode/gecode4.yap /home/vsc/github/yap-6.3/packages/gecode/gecode3_yap_hand_written.yap /home/vsc/github/yap-6.3/packages/gecode/gecode4_yap_hand_written.yap */CMakeFiles/* *~ */ 
 
 # The EXCLUDE_SYMLINKS tag can be used to select whether or not files or
 # directories that are symbolic links (a Unix file system feature) are excluded
diff --git a/pl/arrays.yap b/pl/arrays.yap
index 54c1be381..d14d6ed3c 100644
--- a/pl/arrays.yap
+++ b/pl/arrays.yap
@@ -15,10 +15,13 @@
 *									 *
 *************************************************************************/
 
-%% @{
-
 /**
+
+@file arrays.yap
+
 @addtogroup YAPArrays
+
+@{
 */
 %
 % These are the array built-in predicates. They will only work if
diff --git a/pl/debug.yap b/pl/debug.yap
index d7ae4a411..eeedbbfc5 100644
--- a/pl/debug.yap
+++ b/pl/debug.yap
@@ -284,28 +284,30 @@ be lost.
 /**
   * @pred $trace( +Goal )
   *
+  * This launches a goal from the debugger with the  call. It must:
+  *  - disable user interaction;
+  *  - verify whether debugging is still ok;
+  *  - enter the debugger core.
+  * The top gated_call should set up creeping for the next call.
   *
-  * @param _Goal_ is the goal to be examined.
+  * @param _Mod_:_Goal_ is the goal to be examined.
   * @return `call(Goal)`
 */
-% handle suspended goals
-% take care with hidden goals.
-%
-% $trace may be called from user code, so be careful.
 '$trace'([Mod|G]) :-
-        '$stop_creeping'(_),
+    '$stop_creeping'(_),
 	current_prolog_flag(debug, false),
 	!,
 	'$execute_nonstop'(G,Mod).
 '$trace'([Mod|G]) :-
 	CP is '$last_choice_pt',
 	gated_call(
-	'$debugger_input',
-		   '$trace_query'(G, Mod, CP, not_expanded),
-		   E,
-		   '$continue_debugging'(E)
+		'$debugger_input',
+	    '$trace_query'(G, Mod, CP, not_expanded),
+	     E,
+		'$continue_debugging'(E)
 		  ).
 
+
 '$continue_debugging'(_) :- !,
 	current_prolog_flag(debug, false).
 '$continue_debugging'(exit) :- !, '$creep'.
@@ -361,10 +363,12 @@ be lost.
 
 /**
   * @pred debugger_input.
-  * name of stream used for debugging,
-  * must be always connected to a tty.
   *
-  * '$debugger_input': try to connect the debugger to an open terminal.
+  * set up the stream used for debugging,
+  * - must be interactive.
+  * - default is `user_input`, but /dev/tty and CONIN$ can be used directly if
+  *   user_input is bound to a file.
+  *
 */
 '$debugger_input' :-
 	stream_property(_,alias(debugger_input)),
@@ -388,10 +392,13 @@ be lost.
 
 %% @pred '$trace_query'( +G, +M, +CP, +Expanded)
 %
-%% debug a complex query
-
+% debug a complex query
+% 
+'$trace_query'(V, M, CP, _) :-
+	'$creep',
+	!,
+	'$call'(V,M,V,CP).
 '$trace_query'(V, M, CP, _) :-
-	'$stop_creeping'(_),
 	var(V), !,
 	'$trace_query'(call(V), M, CP, _).
 '$trace_query'(!, _, CP, _) :-
@@ -459,7 +466,7 @@ be lost.
 
 %% @pred $trace_goal( +Goal, +Module, +CallId, +CallInfo)
 %%
-%% Actually debugs a
+%% Actuallb sy debugs a
 %% goal!
 '$trace_goal'(G, M, GoalNumber, _H) :-
 	(
@@ -490,18 +497,18 @@ be lost.
         '$debugger_expand_meta_call'(M:G, [], G1),
 	strip_module(G1, MF, NG),
 	gated_call(
-		   '$enter_trace'(GoalNumber, G, M, H, _What),
+		   '$enter_trace'(GoalNumber, G, M, H),
 		   '$execute_nonstop'(NG,MF),
 		   Port,
 		   '$trace_port'(Port, GoalNumber, G, M, true, H)
                   ).
 % system_
 '$trace_goal'(G, M, GoalNumber, H) :-
-	(
-	 '$is_opaque_predicate'(G, M)
-	;
-	 'strip_module'(M:G, prolog, _NG)
-	),
+	   (
+	    '$is_opaque_predicate'(G, M)
+	       ;
+	     'strip_module'(M:G, prolog, _NG)
+	   ),
 	!,
 	gated_call(
 		   '$enter_trace'(GoalNumber, G, M, H),
@@ -510,12 +517,24 @@ be lost.
 		   '$trace_port'(Port, GoalNumber, G, M, true, H)
                   ).
 '$trace_goal'(G, M, GoalNumber, H) :-
-	gated_call(
-		   '$enter_trace'(GoalNumber, G, M, H),
-		   '$debug'( GoalNumber, G, M, H),
-		   Port,
-		   '$trace_port'(Port, GoalNumber, G, M, true, H)
-                  ).
+	     gated_call(
+		          '$enter_trace'(GoalNumber, G, M, H),
+		          '$debug'( GoalNumber, G, M, H),
+		          Port,
+		          '$trace_port'(Port, GoalNumber, G, M, true, H)
+              ).
+
+
+/**
+ * @pred '$enter_trace'(+L, 0:G, +Module, +Info)
+ * 
+ * call goal: prelims
+ *  
+ * @parameter _Module_:_G_ 
+ * @parameter _L_ is the list of active goals
+ * @parameter _Info_ describes the goal
+ * 
+ */
 '$enter_trace'(L, G, Module, Info) :-
         /* get goal no.	*/
         ( var(L) ->
@@ -543,6 +562,19 @@ be lost.
         /* and save it globaly		*/
         '__NB_setval__'('$spy_gn',L1).
 
+/**
+ * @pred '$enter_trace'(+L, 0:G, +Module, +Info)
+ * 
+ * call goal: setup the diferrent cases
+ *  - zip, just run through
+ *  - source, call an interpreter
+ *  - compiled code: try black magic.
+ *  
+ * @parameter _Module_:_G_ 
+ * @parameter _GoalNumber_ identifies the active goal
+ * @parameter _Info_ describes the goal
+ * 
+ */
 '$debug'(_, G, M, _H) :-
         '__NB_getval__'('$debug_status',state(zip,_Border,_), fail),
 	!,
@@ -555,12 +587,24 @@ be lost.
 	'$creep_step'(GoalNumber, G, M, Info).
 
 
-
+/**
+ * @pred '$trace_go'(+L, 0:G, +Module, +Info)
+ * 
+ * It needs to run in two separate steps:
+ *    1. Select a clause;
+ *    2. Debug it.
+ * We use a marker to track who we are in gated_call.
+ *  
+ * @parameter _Module_:_G_ 
+ * @parameter _GoalNumber_ identifies the active goal
+ * @parameter _Info_ describes the goal
+ * 
+ */
 '$trace_go'(GoalNumber, G, M, Info) :-
-	X=marker(_,M,G),
+		X=marker(_,M,G),
         CP is '$last_choice_pt',
         clause(M:G, Cl, _),
-	'$retry_clause'(GoalNumber, G, M, Info, X),
+		'$retry_clause'(GoalNumber, G, M, Info, X),
         '$trace_query'(Cl, M, CP, expanded).
 
 '$creep_step'(GoalNumber, G, M, Info) :-
@@ -592,7 +636,7 @@ be lost.
     GoalNumber =< G0,
     !,
     fail.
-'$re_trace_query'(forward(redo,G0), G, M, GoalNumber, H) :-
+    '$re_trace_query'(forward(redo,G0), G, M, GoalNumber, H) :-
     GoalNumber > G0,
     !,
     catch(
@@ -638,7 +682,7 @@ be lost.
 '$TraceError'(forward(redo,_G0), _, _, _, _).
 %%% - backtrack long distance
 '$TraceError'(forward(fail,_G0),GoalNumber, _, _, _) :- !,
-	throw(error(fail(GoalNumber))).
+	throw(debugger(fail,GoalNumber)).
 %%%
 %%% - forward through the debugger
 '$TraceError'(forward('$wrapper',Event), _, _, _, _) :-
diff --git a/pl/flags.yap b/pl/flags.yap
index 6ec93294e..298666c4f 100644
--- a/pl/flags.yap
+++ b/pl/flags.yap
@@ -17,8 +17,8 @@
 /**
  * @file flagd.ysp
  *
- * @defgroup Flags Yap Flags
- * @{}
+ * @defgroup YAPFlags Yap Flags
+ *
  * @ingroup builtins
  * 
  */
diff --git a/pl/top.yap b/pl/top.yap
index 87ab54131..e79aea434 100644
--- a/pl/top.yap
+++ b/pl/top.yap
@@ -670,6 +670,7 @@ write_query_answer( Bindings ) :-
         ;
 	'$call'(Z,CP,G0,M)
 	).
+
 '$call'((X*->Y| Z),CP,G0,M) :- !,
 	(
 	 '$current_choice_point'(DCP),
@@ -831,7 +832,7 @@ gated_call(Setup, Goal, Catcher, Cleanup) :-
         Task0 = cleanup( All, Catcher, Cleanup, Tag, true, CP0),
 	TaskF = cleanup( All, Catcher, Cleanup, Tag, false, CP0),
 	'$tag_cleanup'(CP0, Task0),
-	'$execute'( Goal ),
+	'$execute_nonstop'( Goal ),
 	'$cleanup_on_exit'(CP0, TaskF).
 
 
@@ -965,7 +966,7 @@ catch(G, C, A) :-
   ).
 '$catch'(_,C,A) :-
 	'$get_exception'(C0),
-	( C = C0 -> '$execute'(A) ; throw(C0) ).
+	( C = C0 -> '$execute_nonstop'(A, prolog) ; throw(C0) ).
 
 % variable throws are user-handled.
 '$run_catch'(G,E) :-