diff --git a/H/Regs.h b/H/Regs.h
index 934c67d67..d51a155b0 100644
--- a/H/Regs.h
+++ b/H/Regs.h
@@ -110,9 +110,6 @@ typedef struct
     ADDR   AuxTop_;		/* 10 Auxiliary stack top                     */
 /* visualc*/
     CELL   EX_;	    	        /* 18                                         */
-#ifdef COROUTINING
-    Term  DelayedVars_;         /* maximum number of attributed variables     */
-#endif
     Term  CurrentModule_;
 #if defined(SBA) || defined(TABLING)
     CELL *H_FZ_;
@@ -697,9 +694,6 @@ EXTERN inline void restore_B(void) {
 #define frame_tail    Yap_REGS.frame_tail_
 #endif /* SBA */
 #endif /* YAPOR */
-#ifdef COROUTINING
-#define DelayedVars   Yap_REGS.DelayedVars_
-#endif
 #if defined(YAPOR) || defined(TABLING)
 #define LOCAL	      Yap_REGS.LOCAL_
 #endif
diff --git a/H/TermExt.h b/H/TermExt.h
index b893ac534..55359db18 100644
--- a/H/TermExt.h
+++ b/H/TermExt.h
@@ -58,6 +58,14 @@ blob_type;
 #define   FunctorDouble   ((Functor)(double_e))
 #define   EndSpecials     (double_e+sizeof(Functor *))
 
+inline EXTERN int IsAttVar (CELL *pt);
+
+inline EXTERN int
+IsAttVar (CELL *pt)
+{
+  return (pt)[-1] == (CELL)attvar_e;
+}
+
 typedef enum
   {
     BIG_INT =      0x01,
@@ -452,7 +460,7 @@ inline EXTERN Int IsAttachedTerm (Term);
 inline EXTERN Int
 IsAttachedTerm (Term t)
 {
-  return (Int) ((IsVarTerm (t) && VarOfTerm (t) < H0));
+  return (Int) ((IsVarTerm (t) && IsAttVar(VarOfTerm(t))));
 }
 
 
@@ -463,8 +471,7 @@ inline EXTERN Int SafeIsAttachedTerm (Term);
 inline EXTERN Int
 SafeIsAttachedTerm (Term t)
 {
-  return (Int) ((IsVarTerm (t) && VarOfTerm (t) < H0
-		 && VarOfTerm (t) >= (CELL *) Yap_GlobalBase));
+  return (Int) (IsVarTerm (t) && IsAttVar(VarOfTerm(t)));
 }
 
 
diff --git a/H/YapHeap.h b/H/YapHeap.h
index 86eca7411..29ba8e612 100755
--- a/H/YapHeap.h
+++ b/H/YapHeap.h
@@ -91,7 +91,6 @@ typedef struct restore_info {
   CELL    *g_split;
   tr_fr_ptr old_TR;  
   CELL    *old_GlobalBase, *old_H, *old_H0;
-  CELL    *old_DelayTop, *current_DelayTop;
   ADDR     old_TrailBase, old_TrailTop;
   ADDR     old_HeapBase, old_HeapTop;
 } restoreinfo;
@@ -183,7 +182,6 @@ typedef struct worker_local_struct {
   int allow_restart;
   Term global_arena;
   UInt global_arena_overflows; 
-  Term global_delay_arena;
   yamop trust_lu_code[3];
 #if (defined(YAPOR) || defined(TABLING) ) && defined(THREADS)
 #ifdef YAPOR
@@ -293,8 +291,6 @@ extern struct various_codes *Yap_heap_regs;
 #define  OldTrailTop              RINFO.old_TrailTop
 #define  OldHeapBase              RINFO.old_HeapBase
 #define  OldHeapTop               RINFO.old_HeapTop
-#define  OldDelayTop              RINFO.old_DelayTop
-#define  CurrentDelayTop          RINFO.current_DelayTop
 #define  ClDiff                   RINFO.cl_diff
 #define  GDiff                    RINFO.g_diff
 #define  GDiff0                   RINFO.g_diff0
@@ -360,7 +356,6 @@ extern struct various_codes *Yap_heap_regs;
 #define  GlobalArena              Yap_heap_regs->WL.global_arena
 #define  GlobalArenaOverflows     Yap_heap_regs->WL.global_arena_overflows
 #define  Yap_AllowRestart         Yap_heap_regs->WL.allow_restart
-#define  GlobalDelayArena         Yap_heap_regs->WL.global_delay_arena
 
 #define  PredHashInitialSize      1039L
 #define  PredHashIncrement        7919L
diff --git a/H/Yapproto.h b/H/Yapproto.h
index 65826d352..6bf271e5c 100644
--- a/H/Yapproto.h
+++ b/H/Yapproto.h
@@ -190,6 +190,7 @@ void	STD_PROTO(Yap_inform_profiler_of_clause,(struct yami *,struct yami *,struct
 
 /* globals.c */
 Term	STD_PROTO(Yap_NewArena,(UInt,CELL *));
+CELL   *STD_PROTO(Yap_GetFromArena,(Term *,UInt,UInt));
 void	STD_PROTO(Yap_InitGlobals,(void));
 Term	STD_PROTO(Yap_SaveTerm, (Term));
 Term	STD_PROTO(Yap_SetGlobalVal, (Atom, Term));
diff --git a/H/Yatom.h b/H/Yatom.h
index 900f0596a..5496ed230 100644
--- a/H/Yatom.h
+++ b/H/Yatom.h
@@ -216,6 +216,7 @@ typedef struct global_entry
   struct AtomEntryStruct *AtomOfGE; /* parent atom for deletion */
   struct global_entry *NextGE; /* linked list of global entries */
   Term  global;	/* index in module table                */
+  Term  AttChain;	/* index in module table                */
 } GlobalEntry;
 
 
diff --git a/H/amidefs.h b/H/amidefs.h
index 5e7dc7553..428cf8d9d 100644
--- a/H/amidefs.h
+++ b/H/amidefs.h
@@ -65,6 +65,30 @@
 #include <stdio.h>
 #endif 
 
+#ifdef FROZEN_STACKS
+#ifdef SBA
+#define PROTECT_FROZEN_H(CPTR)                                  \
+       ((Unsigned((Int)((CPTR)->cp_h)-(Int)(H_FZ)) <            \
+	 Unsigned((Int)(B_FZ)-(Int)(H_FZ))) ?                   \
+	(CPTR)->cp_h : H_FZ)
+#define PROTECT_FROZEN_B(CPTR)                                  \
+       ((Unsigned((Int)(CPTR)-(Int)(H_FZ)) <                    \
+	 Unsigned((Int)(B_FZ)-(Int)(H_FZ)))  ?                  \
+	(CPTR) : B_FZ)
+	 /*
+#define PROTECT_FROZEN_H(CPTR) ((CPTR)->cp_h > H_FZ && (CPTR)->cp_h < (CELL *)B_FZ ? (CPTR)->cp_h : H_FZ )
+
+#define PROTECT_FROZEN_B(CPTR)  ((CPTR) < B_FZ && (CPTR) > (choiceptr)H_FZ ? (CPTR) : B_FZ )
+	 */
+#else /* TABLING */
+#define PROTECT_FROZEN_B(CPTR)  (YOUNGER_CP(CPTR, B_FZ) ? CPTR        : B_FZ)
+#define PROTECT_FROZEN_H(CPTR)  (((CPTR)->cp_h > H_FZ) ? (CPTR)->cp_h : H_FZ)
+#endif /* SBA */
+#else
+#define PROTECT_FROZEN_B(CPTR)  (CPTR)
+#define PROTECT_FROZEN_H(CPTR)  (CPTR)->cp_h
+#endif /* FROZEN_STACKS */
+
 #if ALIGN_LONGS
 /*   */ typedef Int DISPREG;
 /*   */ typedef CELL SMALLUNSGN;
diff --git a/H/attvar.h b/H/attvar.h
index efe4493b7..e1ed2747c 100644
--- a/H/attvar.h
+++ b/H/attvar.h
@@ -42,24 +42,24 @@ Each attribute contains;
 */
 
 typedef struct attvar_struct {
+  Functor AttFunc;      /* functor for attvar */
   Term Done;		/* if unbound suspension active, if bound terminated */
   Term Value;           /* value the variable will take */
   Term Atts; /* actual data */
 } attvar_record;
 
+#define ATT_RECORD_ARITY  3
+
 /*********** tags for suspension variables */
 
-#define AbsAttVar(attvar_ptr)	AbsAppl(((CELL *)(attvar_ptr)))
-#define RepAttVar(val)		((attvar_record *)RepAppl(val))
-
-static inline attvar_record *
-DelayTop(void) {
-  return (attvar_record *)Yap_ReadTimedVar(DelayedVars);
+static inline Term
+AbsAttVar(attvar_record *attvar_ptr) {
+  return attvar_ptr->Done;
 }
 
-static inline void
-SetDelayTop(attvar_record *new_top) {
-  Yap_UpdateTimedVar(DelayedVars, (CELL)new_top);
+static inline attvar_record *
+RepAttVar(Term *var_ptr) {
+  return (attvar_record *)(var_ptr-1);
 }
 
 #endif
diff --git a/H/rheap.h b/H/rheap.h
index 1c4041c1a..9e125abca 100755
--- a/H/rheap.h
+++ b/H/rheap.h
@@ -1024,10 +1024,6 @@ restore_codes(void)
 	AbsAppl(PtoGloAdjust(RepAppl(Yap_heap_regs->wl.global_arena)));
     }
   }
-  if (Yap_heap_regs->wl.global_delay_arena) {
-    Yap_heap_regs->wl.global_delay_arena =
-      GlobalAdjust(Yap_heap_regs->wl.global_delay_arena);
-  }
   Yap_heap_regs->wl.allow_restart = FALSE;
 #endif
 #endif