diff --git a/C/agc.c b/C/agc.c
index 9a8ef23fe..ce32dc9c1 100644
--- a/C/agc.c
+++ b/C/agc.c
@@ -312,9 +312,9 @@ mark_global_cell(CELL *pt)
 #endif
     case (CELL)FunctorBigInt:
       {
-	Int sz = 2 +
+	Int sz = 3 +
 	  (sizeof(MP_INT)+
-	   (((MP_INT *)(pt+1))->_mp_alloc*sizeof(mp_limb_t)))/sizeof(CELL);
+	   (((MP_INT *)(pt+2))->_mp_alloc*sizeof(mp_limb_t)))/sizeof(CELL);
 	return pt + sz;
       }
     case (CELL)FunctorLongInt:
diff --git a/C/bignum.c b/C/bignum.c
index 66bf3672c..2b93b5c04 100644
--- a/C/bignum.c
+++ b/C/bignum.c
@@ -34,7 +34,7 @@ Term
 Yap_MkBigIntTerm(MP_INT *big)
 {
   Int nlimbs;
-  MP_INT *dst = (MP_INT *)(H+1);
+  MP_INT *dst = (MP_INT *)(H+2);
   CELL *ret = H;
 
   if (mpz_fits_slong_p(big)) {
@@ -46,6 +46,7 @@ Yap_MkBigIntTerm(MP_INT *big)
     return TermNil;
   }
   H[0] = (CELL)FunctorBigInt;
+  H[1] = BIG_INT;
 
   dst->_mp_size = big->_mp_size;
   dst->_mp_alloc = big->_mp_alloc;
@@ -59,7 +60,7 @@ Yap_MkBigIntTerm(MP_INT *big)
 MP_INT *
 Yap_BigIntOfTerm(Term t)
 {
-  MP_INT *new = (MP_INT *)(RepAppl(t)+1);
+  MP_INT *new = (MP_INT *)(RepAppl(t)+2);
 
   new->_mp_d = (mp_limb_t *)(new+1);
   return(new);
@@ -98,7 +99,8 @@ p_is_bignum(void)
 {
 #ifdef USE_GMP
   Term t = Deref(ARG1);
-  return(IsNonVarTerm(t) && IsApplTerm(t) && FunctorOfTerm(t) == FunctorBigInt);
+  return(
+	 IsNonVarTerm(t) && IsApplTerm(t) && FunctorOfTerm(t) == FunctorBigInt);
 #else
   return FALSE;
 #endif
diff --git a/C/c_interface.c b/C/c_interface.c
index 9d76e14fe..fe3e462b7 100644
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -676,7 +676,8 @@ YAP_MkBlobTerm(unsigned int sz)
   }
   I = AbsAppl(H);
   H[0] = (CELL)FunctorBigInt;
-  dst = (MP_INT *)(H+1);
+  H[1] = BIG_INT;
+  dst = (MP_INT *)(H+2);
   dst->_mp_size = 0L;
   dst->_mp_alloc = sz;
   H += (1+sizeof(MP_INT)/sizeof(CELL));
diff --git a/C/dbase.c b/C/dbase.c
index 4aa457644..53ca78fc8 100644
--- a/C/dbase.c
+++ b/C/dbase.c
@@ -602,13 +602,14 @@ copy_big_int(CELL *st, CELL *pt)
 {
   Int sz = 
     sizeof(MP_INT)+
-    (((MP_INT *)(pt+1))->_mp_alloc*sizeof(mp_limb_t));
+    (((MP_INT *)(pt+2))->_mp_alloc*sizeof(mp_limb_t));
 
   /* first functor */
   st[0] = (CELL)FunctorBigInt;
+  st[1] = pt[1];
   /* then the actual number */
-  memcpy((void *)(st+1), (void *)(pt+1), sz);
-  st = st+1+sz/CellSize;
+  memcpy((void *)(st+2), (void *)(pt+2), sz);
+  st = st+2+sz/CellSize;
   /* then the tail for gc */ 
   st[0] = EndSpecials;
   return st+1;
@@ -703,7 +704,7 @@ static CELL *MkDBTerm(register CELL *pt0, register CELL *pt0_end,
 	  continue;
 #ifdef USE_GMP
 	case (CELL)FunctorBigInt:
-	  CheckDBOverflow(2+Yap_SizeOfBigInt(d0));
+	  CheckDBOverflow(3+Yap_SizeOfBigInt(d0));
 	  /* first thing, store a link to the list before we move on */
 	  *StoPoint++ = AbsAppl(CodeMax);
 	  CodeMax = copy_big_int(CodeMax, ap2);
diff --git a/C/globals.c b/C/globals.c
index 0092c87b9..c2aa6798b 100644
--- a/C/globals.c
+++ b/C/globals.c
@@ -89,7 +89,8 @@ CreateNewArena(CELL *ptr, UInt size)
     MP_INT *dst;
 
     ptr[0] = (CELL)FunctorBigInt;
-    dst = (MP_INT *)(ptr+1);
+    ptr[1] = EMPTY_ARENA;
+    dst = (MP_INT *)(ptr+2);
     dst->_mp_size = 0L;
     dst->_mp_alloc = arena2big_sz(size);
     ptr[size-1] = EndSpecials;
diff --git a/C/grow.c b/C/grow.c
index 76c5dec33..817169a76 100644
--- a/C/grow.c
+++ b/C/grow.c
@@ -467,9 +467,9 @@ AdjustGlobal(long sz)
 #if USE_GMP
 	case (CELL)FunctorBigInt:
 	  {
-	    Int sz = 1+
+	    Int sz = 2+
 	      (sizeof(MP_INT)+
-	       (((MP_INT *)(pt+1))->_mp_alloc*sizeof(mp_limb_t)))/CellSize;
+	       (((MP_INT *)(pt+2))->_mp_alloc*sizeof(mp_limb_t)))/CellSize;
 	    pt += sz;
 	  }
 	  break;
diff --git a/C/heapgc.c b/C/heapgc.c
index 4d9c87b12..36b28a437 100644
--- a/C/heapgc.c
+++ b/C/heapgc.c
@@ -1346,8 +1346,8 @@ mark_variable(CELL_PTR current)
 	POP_CONTINUATION();
       case (CELL)FunctorBigInt:
 	{
-	  UInt sz = (sizeof(MP_INT)+
-		     ((MP_INT *)(next+1))->_mp_alloc*sizeof(mp_limb_t))/CellSize;
+	  UInt sz = (sizeof(MP_INT)+1+
+		     ((MP_INT *)(next+2))->_mp_alloc*sizeof(mp_limb_t))/CellSize;
 	  MARK(next);
 	  /* size is given by functor + friends */
 	  if (next < HGEN)
diff --git a/C/utilpreds.c b/C/utilpreds.c
index b4c879f0b..2b2d5bd35 100644
--- a/C/utilpreds.c
+++ b/C/utilpreds.c
@@ -1164,8 +1164,8 @@ SizeOfExtension(Term t)
     return 0;
   }
   if (f== FunctorBigInt) {
-    CELL *pt = RepAppl(t)+1;
-    return 2+sizeof(MP_INT)+(((MP_INT *)(pt+1))->_mp_alloc*sizeof(mp_limb_t));
+    CELL *pt = RepAppl(t)+2;
+    return 3+sizeof(MP_INT)+(((MP_INT *)(pt))->_mp_alloc*sizeof(mp_limb_t));
   }
   return 0;
 }
@@ -1634,8 +1634,8 @@ hash_complex_term(register CELL *pt0,
 	    {
 	      CELL *pt = RepAppl(d0);
 	      Int sz = 
-		sizeof(MP_INT)+
-		(((MP_INT *)(pt+1))->_mp_alloc*sizeof(mp_limb_t));
+		sizeof(MP_INT)+1+
+		(((MP_INT *)(pt+2))->_mp_alloc*sizeof(mp_limb_t));
 
 	      if (st + (1024 + sz/CellSize) >= ASP) {
 		goto global_overflow;
diff --git a/C/write.c b/C/write.c
index a52415db4..dd422bdf4 100644
--- a/C/write.c
+++ b/C/write.c
@@ -537,9 +537,9 @@ writeTerm(Term t, int p, int depth, int rinfixarg, struct write_globs *wglb)
 	{
 	  MP_INT *big = Yap_BigIntOfTerm(t);
 	  char *s = (char *)TR;
-	  if (s+2+mpz_sizeinbase(big, 10) >= Yap_TrailTop) {
+	  if (s+3+mpz_sizeinbase(big, 10) >= Yap_TrailTop) {
 	    s = (char *)H;
-	    if (s+2+mpz_sizeinbase(big, 10) >= (char *)ASP) {
+	    if (s+3+mpz_sizeinbase(big, 10) >= (char *)ASP) {
 	      return;
 	    }
 	  }
diff --git a/H/TermExt.h b/H/TermExt.h
index d2063630b..deba53364 100644
--- a/H/TermExt.h
+++ b/H/TermExt.h
@@ -56,6 +56,16 @@ blob_type;
 #define   FunctorDouble   ((Functor)(double_e))
 #define   EndSpecials     (double_e+sizeof(Functor *))
 
+typedef enum
+  {
+    BIG_INT =      0x01,
+    BIG_RATIONAL = 0x02,
+    BIG_FLOAT =    0x04,
+    EMPTY_ARENA =  0x10,
+    ARRAY_INT =    0x21,
+    ARRAY_FLOAT =  0x22
+  } 
+big_blob_type;
 
 inline EXTERN blob_type BlobOfFunctor (Functor f);
 
@@ -87,7 +97,7 @@ typedef struct
   /* what to do if someone wants to copy our constraint */
   int (*copy_term_op) (CELL *, struct cp_frame **, CELL *);
   /* copy the constraint into a term and back */
-    Term (*to_term_op) (CELL *);
+  Term (*to_term_op) (CELL *);
   int (*term_to_op) (Term, Term);
   /* op called to do marking in GC */
   void (*mark_op) (CELL *);
diff --git a/H/absmi.h b/H/absmi.h
index 7e4f26d64..712ef8733 100644
--- a/H/absmi.h
+++ b/H/absmi.h
@@ -1374,7 +1374,7 @@ loop:
 	    return (FALSE);
 #ifdef USE_GMP
 	  case (CELL)FunctorBigInt:
-	    if (IsBigIntTerm(d1) && mpz_cmp((MP_INT *)(ap2+1),Yap_BigIntOfTerm(d1)) == 0) continue;
+	    if (IsBigIntTerm(d1) && mpz_cmp((MP_INT *)(ap2+2),Yap_BigIntOfTerm(d1)) == 0) continue;
 	    UNWIND_CUNIF();
 	    return (FALSE);
 #endif /* USE_GMP */
diff --git a/LGPL/chr b/LGPL/chr
index 293457c65..6f4f1a9f1 160000
--- a/LGPL/chr
+++ b/LGPL/chr
@@ -1 +1 @@
-Subproject commit 293457c65497bf63027c24cf954e6b4965f70df3
+Subproject commit 6f4f1a9f182a6ea62de4683ea9f5923ccf20257f
diff --git a/Makefile.in b/Makefile.in
index ac28d98ae..ac8a0a9e5 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -149,7 +149,8 @@ C_SOURCES= \
 	$(srcdir)/C/corout.c $(srcdir)/C/dbase.c $(srcdir)/C/dlmalloc.c \
 	$(srcdir)/C/errors.c \
 	$(srcdir)/C/eval.c $(srcdir)/C/exec.c \
-	$(srcdir)/C/globals.c $(srcdir)/C/gprof.c $(srcdir)/C/grow.c \
+	$(srcdir)/C/globals.c $(srcdir)/C/gmp_support.c \
+	$(srcdir)/C/gprof.c $(srcdir)/C/grow.c \
 	$(srcdir)/C/heapgc.c $(srcdir)/C/index.c	   \
 	$(srcdir)/C/init.c $(srcdir)/C/inlines.c	   \
 	$(srcdir)/C/iopreds.c $(srcdir)/C/depth_bound.c \
@@ -223,7 +224,7 @@ ENGINE_OBJECTS = \
 	bignum.o bb.o \
 	cdmgr.o cmppreds.o compiler.o computils.o \
 	corout.o cut_c.o dbase.o dlmalloc.o errors.o eval.o \
-	exec.o globals.o gprof.o grow.o \
+	exec.o globals.o gmp_support.o gprof.o grow.o \
 	heapgc.o index.o init.o  inlines.o \
 	iopreds.o depth_bound.o mavar.o \
 	myddas_mysql.o myddas_odbc.o myddas_shared.o myddas_initialization.o \
@@ -343,6 +344,9 @@ exec.o: $(srcdir)/C/exec.c
 globals.o: $(srcdir)/C/globals.c
 	$(CC) -c $(CFLAGS) $(srcdir)/C/globals.c -o $@
 
+gmp_support.o: $(srcdir)/C/gmp_support.c
+	$(CC) -c $(CFLAGS) $(srcdir)/C/gmp_support.c -o $@
+
 gprof.o: $(srcdir)/C/gprof.c
 	$(CC) -c $(CFLAGS) $(srcdir)/C/gprof.c -o $@
 
diff --git a/README b/README
index 3985da8b0..3824d89fc 100644
--- a/README
+++ b/README
@@ -1,9 +1,9 @@
 
 
-			README for Yap 5.1
+			README for Yap6
 
 
-This directory contains a release of the Yap 5.1.* Prolog system,
+This directory contains a release of the Yap 6.0.* Prolog system,
 originally developed at the Universidade do Porto by Luis Damas and
 Vitor Santos Costa, with contributions from the Edinburgh Prolog
 library, the C-Prolog manual authors, Ricardo Lopes, Ricardo Rocha,
@@ -12,17 +12,14 @@ Jan Wielemaker, Paul Singleton, Fred Dushin, Jan Wielemaker, Markus
 Triska, and many others. You should read the rest of this file for
 information on what Yap is and for instructions on how to build it.
 
-YAP 52 is known to build with many versions of gcc (<= gcc-2.7.2, >=
-gcc-2.8.1, >= egcs-1.0.1, gcc-2.95.*) and on a variety of Linux,
-MacOSX, and Unix'es: SunOS 4.1, Solaris 2.*, Irix 5.2, HP-UX 10.20,
-Dec Alpha Unix, Linux 1.2 and Linux 2.* (RedHat 4.0 through 5.2,
-Debian 2.*) in both the x86 and alpha platforms. It has been built on
-Windows XP using cygwin/mingw from Cygnus Solutions. and on MaxO
+YAP 6 has been built with several versions on GCC on a variety of
+Linux, MacOSX. It has been built on Windows XP and VISTA using
+cygwin/mingw from Cygnus Solutions.
 
 The main core of the YAP distribution is distributed under a dual
 license: the Perl Artistic license 2 and the FSF's LGPL. The YAP
 distribution also contains files distributed under the LGPL
-exclusively, and under the GPL. 
+exclusively, and under the GPL.
 
 The YAP distribution includes several packages ported to Yap, such as
 Pillow, JPL, CLP(R) and CHR. We would like to take the opportunity to
@@ -69,7 +66,20 @@ full compatibility, and the manual describes what is still
 missing. The manual also includes a (largely incomplete) comparison
 with SICStus Prolog.
  
-2. How to compile YAP
+2. Obtaining YAP's development sources.
+
+YAP is now being maintained using the git source management system. A
+public repository is available at 
+
+http://gitorious.org/projects/yap-git
+
+Please use
+
+git clone git://gitorious.org/yap-git/mainline.git
+
+to obtain a copy of the current YAP tree.
+
+3. How to compile YAP
 
 To compile YAP just do:
 
@@ -96,7 +106,7 @@ To compile YAP just do:
 In most systems you will need to be superuser in order to do "make
 install" and "make info" on the standard directories.
 
-2.1 Where to install Yap
+3.1 Where to install Yap
 
  YAP uses autoconf. Recent versions of Yap try to follow GNU
 conventions on where to place software. You can use the --prefix
@@ -125,7 +135,7 @@ binary Prolog libraries.
   o INFODIR is where the info help files will be stored. It defaults
 to $(SHAREDIR)/info.
 
-2.2 Which Yap to compile
+3.2 Which Yap to compile
 
 Compiling Yap with the standard options give you a plain vanilla
 Prolog. You can tune Yap to use extra functionality by using the
@@ -155,70 +165,12 @@ supported by one of these three forms. This is still highly experimental.
 
  o --enable-tabling=yes allows tabling support. This is still experimental.
 
-2.3 Porting Yap
+3.3 Porting Yap
 
 The system has been mainly tested with GCC, but we have been able to
-compile versions of Yap under lcc in Linux, Sun's cc compiler, IBM's
-xlc, SGI's cc, HP's cc, and Microsoft's Visual C++ 6.0.
+compile older versions of Yap under lcc in Linux, Sun's cc compiler,
+IBM's xlc, SGI's cc, HP's cc, and Microsoft's Visual C++ 6.0. Recent
+versions of YAP have also been compiled using Intel's lcc.
 
-2.3.1 Yap and GCC
 
-Yap has been developed to take advantage of GCC (but not to depend on
-it). The major advantage of GCC is threaded code and register
-reservation. 
-
-YAP is set by default to compile with the best compilation flags we
-know. Even so, a few specific options can be used depending on the
-architecture:
-
-2.3.1.1 x86
-
-The flag:
-
-	YAP_EXTRAS= ... -DBP_FREE=1
-
-tells us to use the %bp register (frame-pointer) as the emulator's
-program counter. This seems to be stable and should become default
-real soon now.
-
-2.3.1.2 Sparc/Solaris2
-
-Use:
-
-	YAP_EXTRAS= ...   -mno-app-regs -DOPTIMISE_ALL_REGS_FOR_SPARC=1
-
-and YAP will get two extra registers! This trick does not work on
-SunOS 4 machines.
-
-2.3.1.3 Tuning GCC/Yap for your machine model
-
-Versions of GCC can be tweaked for different processors, eg, 486,
-Pentium, PentiumPro, Ultrasparc, Supersparc. Unfortunately, some of
-these tweaks do may make Yap run slower or not at all in other machines
-with the same instruction set, so they cannot be made default.
-
-The best options also depends on the version of GCC you are using, and
-it is a good idea to consult the GCC manual under the menus "Invoking
-GCC"/"Submodel Options". We next describe a few:
-
-(a) GCC up to 2.7.*:
-
-	o 486:
-
-		YAP_EXTRAS= ... -m486 -DBP_FREE=1
-
-	to take advantage of 486 specific optimisations in GCC 2.7.*.
-
-	o Pentium:
-
-		YAP_EXTRAS= ... -m486 -malign-loops=2 -malign-jumps=2 -malign-functions=2
-
-	o PentiumPros are known not to require alignment.
-
-	o Super and UltraSparcs:
-		 YAP_EXTRAS= ... -msupersparc
-
-(b) GCC 2.8.*, EGCS, GCC 2.95.*
-
-	o Check -march=XXX for fun.