diff --git a/mps/src/finalcv.c b/mps/src/finalcv.c
new file mode 100644
index 00000000000..f9857cf043c
--- /dev/null
+++ b/mps/src/finalcv.c
@@ -0,0 +1,207 @@
+/* impl.c.finalcv: FINALIZATION COVERAGE TEST
+ *
+ * $HopeName$
+ * Copyright (C) 1996,1997 Harlequin Group, all rights reserved
+ *
+ * READERSHIP
+ *
+ * Any MPS developer; Any interested QA
+ *
+ * DESIGN
+ *
+ * See design.mps.poolmrg.test.
+ *
+ * PURPOSE
+ *
+ * To test finalization in the MPS.
+ *
+ * DEPENDENCIES
+ *
+ * This test uses the dylan object format, but the reliance on this
+ * particular format is not great and could be removed.
+ *
+ * NOTES
+ *
+ * This code was created by first copying impl.c.weakcv
+ *
+ * .hack.no-interface: There is no MPS interface to PoolMRG, and there
+ * is no MPS interface to finalization.  For the moment this test uses
+ * PoolMRG directly.  Later it will use the MPS interface to
+ * finalization.
+ */
+
+
+#include "testlib.h"
+#include "mps.h"
+#include "mpscamc.h"
+#include "fmtdy.h"
+
+#include "poolmrg.h" /* .hack.no-interface */
+
+#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+
+#define N_ROOTS 20
+#define CHURN_FACTOR 1000
+#define ONE_SLOT_SIZE (3*sizeof(mps_word_t))
+#define MAGIC_0 36	/* source is person.richard */
+
+/* tags an integer according to dylan format */
+static mps_word_t dylan_int(mps_word_t x)
+{
+  return (x << 2)|1;
+}
+
+/* .hack.no-interface */
+static mps_class_t mps_class_mrg(void)
+{
+  return (mps_class_t)PoolClassMRG();
+}
+
+static void *root[N_ROOTS];
+static int rc = 0;			/* return code */
+
+static void
+churn(mps_ap_t ap)
+{
+  int i;
+  mps_addr_t p;
+  mps_res_t e;
+  
+  for(i = 0; i < CHURN_FACTOR; ++i) {
+    do {
+      MPS_RESERVE_BLOCK(e, p, ap, 4096);
+      assert(e == MPS_RES_OK);
+      dylan_init(p, 4096, root, 1);
+    } while(!mps_commit(ap, p, 4096));
+  }
+  p = NULL;
+}
+
+
+static void *
+test(void *arg, size_t s)
+{
+  int i;			/* index */
+  mps_ap_t ap;
+  mps_fmt_t fmt;
+  mps_pool_t amc;
+  mps_pool_t mrg;
+  mps_res_t e;
+  mps_root_t mps_root[2];
+  mps_space_t space;
+  void *mrg_obj[N_ROOTS];
+  void *p = NULL;
+
+  space = (mps_space_t)arg;
+
+  die(mps_fmt_create_A(&fmt, space, dylan_fmt_A()), "fmt_create\n");
+  die(mps_pool_create(&amc, space, mps_class_amc(), fmt),
+      "pool_create amc\n");
+  die(mps_pool_create(&mrg, space, mps_class_mrg()), /* .hack.no-interface */
+      "pool_create mrg\n");
+  die(mps_root_create_table(&mps_root[0], space,
+			     MPS_RANK_EXACT, (mps_rm_t)0,
+			     root, (size_t)N_ROOTS), "root_create\n");
+  die(mps_root_create_table(&mps_root[1], space,
+			     MPS_RANK_EXACT, (mps_rm_t)0,
+			     &p, (size_t)1), "root_create\n");
+  die(mps_ap_create(&ap, amc, MPS_RANK_EXACT), "ap_create\n");
+
+  /* design.mps.poolmrg.test.alloc */
+  for(i = 0; i < N_ROOTS; ++i) {
+    e = mps_alloc(&mrg_obj[i], mrg, sizeof(mps_addr_t));
+    assert(e == MPS_RES_OK);
+  }
+  /* design.mps.poolmrg.test.free */
+  for(i = 0; i < N_ROOTS; ++i) {
+    mps_free(mrg, mrg_obj[i], sizeof(mps_addr_t));
+  }
+
+  /* design.mps.poolmrg.test.rw.a */
+  do {
+    MPS_RESERVE_BLOCK(e, p, ap, ONE_SLOT_SIZE);
+    assert(e == MPS_RES_OK);
+    dylan_init(p, ONE_SLOT_SIZE, root, 1);
+  } while(!mps_commit(ap, p, ONE_SLOT_SIZE));
+
+  /* design.mps.poolmrg.test.rw.alloc */
+  for(i = 0; i < N_ROOTS; ++i) {
+    e = mps_alloc(&mrg_obj[i], mrg, sizeof(mps_addr_t));
+    assert(e == MPS_RES_OK);
+    /* design.mps.poolmrg.test.rw.write */
+    *(mps_addr_t *)mrg_obj[i] = p;
+  }
+  /* design.mps.poolmrg.test.rw.read */
+  for(i = 0; i < N_ROOTS; ++i) {
+    if(*(mps_addr_t *)mrg_obj[i] != p) {
+      printf("Couldn't correctly read reference in guardian object.\n");
+      ++rc;
+    }
+  }
+  /* design.mps.poolmrg.test.rw.free */
+  for(i = 0; i < N_ROOTS; ++i) {
+    mps_free(mrg, mrg_obj[i], sizeof(mps_addr_t));
+  }
+  /* design.mps.poolmrg.test.rw.drop */
+  p = NULL;
+
+  /* design.mps.poolmrg.test.fl.alloc */
+  for(i = 0; i < N_ROOTS; ++i) {
+    do {
+      MPS_RESERVE_BLOCK(e, p, ap, ONE_SLOT_SIZE);
+      assert(e == MPS_RES_OK);
+      dylan_init(p, ONE_SLOT_SIZE, root, 1);
+    } while(!mps_commit(ap, p, ONE_SLOT_SIZE));
+    root[i] = p;
+    /* design.mps.poolmrg.test.fl.tag */
+    ((mps_word_t *)p)[2] = dylan_int(MAGIC_0 ^ i);
+    e = mps_alloc(&mrg_obj[i], mrg, sizeof(mps_addr_t));
+    assert(e == MPS_RES_OK);
+    /* design.mps.poolmrg.test.fl.refer */
+    *(mps_addr_t *)mrg_obj[i] = p;
+  }
+  p = NULL;
+
+  /* design.mps.poolmrg.test.fl.churn */
+  churn(ap);
+  for(i = 0; i < N_ROOTS; ++i) {
+    mps_word_t *o;
+    o = *(mps_addr_t *)mrg_obj[i];
+    if(o[2] != dylan_int(MAGIC_0 ^ i)) {
+      printf("Reference in guardian object has been corrupted or "
+             "referent has been corrupted.\n");
+      ++rc;
+    }
+  }
+  for(i = 0; i < N_ROOTS; ++i) {
+    mps_free(mrg, mrg_obj[i], sizeof(mps_addr_t));
+  }
+
+  mps_ap_destroy(ap);
+  mps_root_destroy(mps_root[0]);
+  mps_root_destroy(mps_root[1]);
+  mps_pool_destroy(amc);
+  mps_pool_destroy(mrg);
+  mps_fmt_destroy(fmt);
+
+  return NULL;
+}
+
+int
+main(void)
+{
+  mps_space_t space;
+  mps_thr_t thread;
+  void *r;
+
+  die(mps_space_create(&space), "space_create\n");
+  die(mps_thread_reg(&thread, space), "thread_reg\n");
+  mps_tramp(&r, test, space, 0);
+  mps_thread_dereg(thread);
+  mps_space_destroy(space);
+
+  return rc;
+}
diff --git a/mps/src/poolmrg.c b/mps/src/poolmrg.c
new file mode 100644
index 00000000000..b41115dcb29
--- /dev/null
+++ b/mps/src/poolmrg.c
@@ -0,0 +1,537 @@
+/* impl.c.poolmrg
+ * 
+ * MANUAL RANK GUARDIAN POOL
+ * 
+ * $HopeName$
+ * Copyright(C) 1995,1997 Harlequin Group, all rights reserved
+ *
+ * READERSHIP
+ *
+ * Any MPS developer.  It will help to read design.mps.poolmrg.
+ * 
+ * DESIGN
+ * 
+ * See design.mps.poolmrg.
+ * 
+ * .update.wasold: At the moment the fix interface provides no way for
+ * the caller to determine whether the referent was in old space.
+ * This is necessary for finalization.  For now, the callsite to fix
+ * (which will need to be changed when the fix interface changes) bears
+ * this tag.
+ *
+ * .access.exact: There is no way to to determine the "correct" rank to
+ * scan at when an access fault is taken (we should use whatever rank the
+ * tracer is at).  We default to scanning at the RankEXACT.
+ *
+ * .improve.rank: At the moment, the pool is a guardian for the final
+ * rank.  It could be generalized to be a guardian for an arbitrary
+ * rank (a guardian for RankEXACT would tell you if the object was
+ * ambiguously referenced, for example).  The code that would need to be
+ * modified bears this tag.
+ */
+
+
+#include "mpm.h"
+#include "poolmrg.h"
+
+
+SRCID(poolmrg, "$HopeName$");
+
+#define MRGSig          ((Sig)0x519B0349)
+
+typedef struct MRGStruct {
+  PoolStruct poolStruct;        /* generic pool structure */
+  RingStruct entry;		/* design.mps.poolmrg.poolstruct.entry */
+  RingStruct exit;		/* design.mps.poolmrg.poolstruct.exit */
+  RingStruct free;		/* design.mps.poolmrg.poolstruct.free */
+  RingStruct group;		/* design.mps.poolmrg.poolstruct.group */
+  Size extendBy;		/* design.mps.poolmrg.extend */
+  Sig sig;			/* impl.h.mps.sig */
+} MRGStruct;
+
+#define PoolPoolMRG(pool) PARENT(MRGStruct, poolStruct, pool)
+
+static Pool MRGPool(MRG mrg);
+
+/* design.mps.poolmrg.guardian.assoc */
+static Index indexOfRefPart(Addr a, Space space)
+{
+  Seg seg;
+  Bool b;
+  Addr base;
+  Addr *pbase, *pa;
+
+  b = SegOfAddr(&seg, space, a);
+  AVER(b);
+  base = SegBase(space, seg);
+  pbase = (Addr *)base;
+  pa = (Addr *)a;
+  return pa - pbase;
+}
+
+/* design.mps.poolmrg.guardian.assoc */
+static Index indexOfLinkPart(Addr a, Space space)
+{
+  Seg seg;
+  Bool b;
+  Addr base ;
+  RingStruct *pbase, *pa;
+
+  b = SegOfAddr(&seg, space, a);
+  AVER(b);
+  base = SegBase(space, seg);
+  pbase = (RingStruct *)base;
+  pa = (RingStruct *)a;
+  return pa - pbase;
+}
+
+#define MRGGroupSig	((Sig)0x5193499b)
+
+typedef struct MRGGroupStruct {
+  Sig sig;                      /* impl.h.misc.sig */
+  RingStruct group;		/* design.mps.poolmrg.group.group */
+  TraceSet grey;                /* design.mps.poolmrg.group.grey */
+  Seg refseg;                   /* design.mps.poolmrg.group.segs */
+  Seg linkseg;                  /* design.mps.poolmrg.group.segs */
+} MRGGroupStruct;
+typedef MRGGroupStruct *MRGGroup;
+
+static void MRGGroupDestroy(MRGGroup group, MRG mrg)
+{
+  Pool pool;
+
+  pool = MRGPool(mrg);
+  RingRemove(&group->group);
+  PoolSegFree(pool, group->refseg);
+  PoolSegFree(pool, group->linkseg);
+  SpaceFree(PoolSpace(pool), (Addr)group, (Size)sizeof(MRGGroupStruct));
+}
+
+static Res MRGGroupCreate(MRGGroup *groupReturn, MRG mrg)
+{
+  Addr base;
+  MRGGroup group;
+  Pool pool;
+  Res res;
+  RingStruct *linkpart;
+  Seg linkseg;
+  Seg refseg;
+  Size linksegsize;
+  Space space;
+  Addr *refpart;
+  Word i, guardians;
+  void *v;
+
+  pool = MRGPool(mrg);
+  space = PoolSpace(pool);
+  res = SpaceAlloc(&v, space, (Size)sizeof(MRGGroupStruct));
+  if(res != ResOK)
+    goto failSpaceAlloc;
+  group = v;
+  res = PoolSegAlloc(&refseg, pool, mrg->extendBy);
+  if(res != ResOK)
+    goto failRefSegAlloc;
+
+  guardians = mrg->extendBy / sizeof(Addr);	/* per seg */
+  linksegsize = guardians * sizeof(RingStruct);
+  linksegsize = SizeAlignUp(linksegsize, VMAlign());
+  res = PoolSegAlloc(&linkseg, pool, linksegsize);
+  if(res != ResOK)
+    goto failLinkSegAlloc;
+
+  /* Link Segment is coerced to an array of RingStructs, each one */
+  /* is appended to the free Ring. */
+  /* The ref part of each guardian is cleared. */
+
+  AVER(guardians > 0);
+  base = SegBase(space, linkseg);
+  linkpart = (RingStruct *)base;
+  refpart = (Addr *)SegBase(space, refseg);
+
+  for(i=0; i<guardians; ++i) {
+    RingInit(&linkpart[i]);
+    RingAppend(&mrg->free, &linkpart[i]);
+    refpart[i] = 0;
+  }
+  AVER((Addr)(&linkpart[i]) <= SegLimit(space, linkseg));
+  AVER((Addr)(&refpart[i]) <= SegLimit(space, refseg));
+  refseg->rank = RankFINAL;
+
+  group->refseg = refseg;
+  group->linkseg = linkseg;
+  refseg->p = group;
+  linkseg->p = group;
+  group->grey = TraceSetEMPTY;
+  RingInit(&group->group);
+  RingAppend(&mrg->group, &group->group);
+  group->sig = MRGGroupSig;
+
+  return ResOK;
+
+failLinkSegAlloc:
+  PoolSegFree(pool, refseg);
+failRefSegAlloc:
+  SpaceFree(space, (Addr)group, (Size)sizeof(MRGGroupStruct)); 
+failSpaceAlloc:
+  return res;
+}
+
+static Res MRGGroupScan(ScanState ss, MRGGroup group, MRG mrg)
+{
+  Addr base;
+  Res res;
+  Space space;
+  Addr *refpart;
+  Word guardians, i;
+  int wasOld = 0;
+
+  space = PoolSpace(MRGPool(mrg));
+
+  ShieldExpose(space, group->refseg);
+
+  guardians = mrg->extendBy / sizeof(Addr);	/* per seg */
+  AVER(guardians > 0);
+  base = SegBase(space, group->refseg);
+  refpart = (Addr *)base;
+  TRACE_SCAN_BEGIN(ss) {
+    for(i=0; i<guardians; ++i) {
+      if(!TRACE_FIX1(ss, refpart[i])) continue;
+      res = TRACE_FIX2(ss, &refpart[i]);	/* .update.wasold */
+      if(res != ResOK) {
+	return res;
+      }
+      if(wasOld && ss->rank == RankFINAL) {	/* .improve.rank */
+	RingStruct *linkpart =
+	  (RingStruct *)SegBase(space, group->linkseg);
+	RingRemove(&linkpart[i]);
+	RingAppend(&mrg->exit, &linkpart[i]);
+      }
+    }
+  } TRACE_SCAN_END(ss);
+
+  group->grey = TraceSetDelete(group->grey, ss->traceId);
+  ShieldLower(space, group->refseg, AccessREAD | AccessWRITE);
+  ShieldCover(space, group->refseg);
+
+  return ResOK;
+}
+
+
+static Bool MRGCheck(MRG mrg);
+
+static Res MRGInit(Pool pool, va_list args)
+{
+  MRG mrg = PoolPoolMRG(pool);
+
+  UNUSED(args);
+  
+  RingInit(&mrg->entry);
+  RingInit(&mrg->exit);
+  RingInit(&mrg->free);
+  RingInit(&mrg->group);
+  mrg->extendBy = ArenaAlign(PoolSpace(pool));
+  mrg->sig = MRGSig;
+
+  AVERT(MRG, mrg);
+
+  return ResOK;
+}
+
+static void MRGFinish(Pool pool)
+{
+  MRG mrg;
+  Ring node;
+
+  AVERT(Pool, pool);
+  mrg = PoolPoolMRG(pool);
+  AVERT(MRG, mrg);
+
+  node = RingNext(&mrg->group);
+  while(node != &mrg->group) {
+    Ring next = RingNext(node);
+    MRGGroup group = RING_ELT(MRGGroup, group, node);
+    MRGGroupDestroy(group, mrg);
+
+    node = next;
+  }
+
+  mrg->sig = SigInvalid;
+}
+
+static Pool MRGPool(MRG mrg)
+{
+  AVERT(MRG, mrg);
+  return &mrg->poolStruct;
+}
+
+static Res MRGAlloc(Addr *pReturn, Pool pool, Size size)
+{
+  Addr *refpart;
+  Bool b;
+  Index gi;
+  MRG mrg;
+  MRGGroup group;
+  MRGGroup junk;		/* .group.useless */
+  Res res;
+  Ring f;
+  Seg seg;
+  Space space;
+
+  AVERT(Pool, pool);
+  mrg = PoolPoolMRG(pool);
+  AVERT(MRG, mrg);
+
+  AVER(pReturn != NULL);
+  AVER(size == sizeof(Addr));	/* design.mps.poolmrg.alloc.one-size */
+
+  space = PoolSpace(pool);
+
+  f = RingNext(&mrg->free);
+
+  /* design.mps.poolmrg.alloc.grow */
+
+  if(f == &mrg->free) {			/* (Ring has no elements) */
+    res = MRGGroupCreate(&junk, mrg);	/* .group.useless: group isn't used */
+    if(res != ResOK) {
+      return res;
+    }
+    f = RingNext(&mrg->free);
+  }
+  AVER(f != &mrg->free);
+
+  /* design.mps.poolmrg.alloc.pop */
+  RingRemove(f);
+  RingAppend(&mrg->entry, f);
+  gi = indexOfLinkPart((Addr)f, space);
+  b = SegOfAddr(&seg, space, (Addr)f);
+  AVER(b);
+  group = seg->p;
+  refpart = (Addr *)SegBase(space, group->refseg);
+
+  /* design.mps.poolmrg.guardian.ref.alloc */
+  *pReturn = (Addr)(&refpart[gi]);
+  return ResOK;
+}
+
+static void MRGFree(Pool pool, Addr old, Size size)
+{
+  MRG mrg;
+  Index gi;
+  Space space;
+  Seg seg;
+  MRGGroup group;
+  Bool b;
+  RingStruct *linkpart;
+
+  AVERT(Pool, pool);
+  mrg = PoolPoolMRG(pool);
+  AVERT(MRG, mrg);
+
+  AVER(old != (Addr)0);
+  AVER(size == sizeof(Addr));
+
+  space = PoolSpace(pool);
+  b = SegOfAddr(&seg, space, old);
+  AVER(b);
+  group = seg->p;
+  linkpart = (RingStruct *)SegBase(space, group->linkseg);
+
+  /* design.mps.poolmrg.guardian.ref.free */
+  gi = indexOfRefPart(old, space);
+
+  AVERT(Ring, &linkpart[gi]);
+  RingRemove(&linkpart[gi]);
+  RingAppend(&mrg->free, &linkpart[gi]);
+  *(Addr *)old = 0;   	/* design.mps.poolmrg.free.overwrite */
+}
+
+static Res MRGDescribe(Pool pool, mps_lib_FILE *stream)
+{
+  MRG mrg;
+  Ring r;
+  Space space;
+  Bool b;
+  MRGGroup group;
+  Index gi;
+  Seg seg;
+  Addr *refpart;
+
+  AVERT(Pool, pool);
+  mrg = PoolPoolMRG(pool);
+  AVERT(MRG, mrg);
+  /* Cannot check stream */
+
+  space = PoolSpace(pool);
+
+  WriteF(stream, "  extendBy $W\n", mrg->extendBy, NULL);
+  WriteF(stream, "  Entry queue:\n", NULL);
+  RING_FOR(r, &mrg->entry) {
+    b = SegOfAddr(&seg, space, (Addr)r);
+    AVER(b);
+    group = seg->p;
+    refpart = (Addr *)SegBase(space, group->refseg);
+    gi = indexOfLinkPart((Addr)r, space);
+    WriteF(stream,
+	   "    at $A ref $A\n",
+	   (WriteFA)&refpart[gi], (WriteFA)refpart[gi],
+	   NULL);
+  }
+  WriteF(stream, "  Exit queue:\n", NULL);
+  RING_FOR(r, &mrg->exit) {
+    b = SegOfAddr(&seg, space, (Addr)r);
+    AVER(b);
+    group = seg->p;
+    refpart = (Addr *)SegBase(space, group->refseg);
+    gi = indexOfLinkPart((Addr)r, space);
+    WriteF(stream,
+	   "    at $A ref $A\n",
+	   (WriteFA)&refpart[gi], (WriteFA)refpart[gi],
+	   NULL);
+  }
+
+  return ResOK;
+}
+
+static void MRGGrey(Pool pool, Space space, TraceId ti)
+{
+  MRG mrg;
+  Ring r;
+
+  AVERT(Pool, pool);
+  mrg = PoolPoolMRG(pool);
+  AVERT(MRG, mrg);
+  AVERT(Space, space);
+  AVERT(TraceId, ti);
+
+  RING_FOR(r, &mrg->group) {
+    MRGGroup group;
+
+    group = RING_ELT(MRGGroup, group, r);
+    group->grey = TraceSetAdd(group->grey, ti);
+    ShieldRaise(space, group->refseg, AccessREAD | AccessWRITE);
+  }
+}
+
+static Res MRGScan(ScanState ss, Pool pool, Bool *finishedReturn)
+{
+  MRG mrg;
+  Res res;
+
+  AVERT(ScanState, ss);
+  AVERT(Pool, pool);
+  mrg = PoolPoolMRG(pool);
+  AVERT(MRG, mrg);
+  AVER(finishedReturn != NULL);
+
+  if(ss->rank == RankFINAL) {
+    Ring r;
+
+    RING_FOR(r, &mrg->group) {
+      MRGGroup group;
+
+      group = RING_ELT(MRGGroup, group, r);
+      if(TraceSetIsMember(group->grey, ss->traceId)) {
+	res = MRGGroupScan(ss, group, mrg);
+	if(res != ResOK) {
+	  return res;
+	}
+	*finishedReturn = FALSE;
+	return ResOK;
+      }
+    }
+  }
+
+  *finishedReturn = TRUE;
+  return ResOK;
+}
+
+/* .amc.copy: This code is an almost exact copy of the analogous
+ * method in impl.c.amc.  This is worrying.
+ */
+static void MRGAccess(Pool pool, Seg seg, AccessSet mode)
+{
+  Space space;
+  MRG mrg;
+  MRGGroup group;
+  Res res;
+  ScanStateStruct ss;
+
+  AVERT(Pool, pool);
+  mrg = PoolPoolMRG(pool);
+  AVERT(MRG, mrg);
+  AVERT(Seg, seg);
+  AVER(seg->pool == pool);
+  /* Cannot check AccessSet */
+
+  space = PoolSpace(pool);
+
+  group = (MRGGroup)seg->p;
+
+  ss.fix = TraceFix;
+  ss.zoneShift = space->zoneShift;
+  ss.summary = RefSetEmpty;
+  ss.space = space;
+  ss.sig = ScanStateSig;
+  ss.rank = RankEXACT;  /* .access.exact */
+  ss.weakSplat = (Addr)0xadd4badd;
+
+  /* impl.c.amc.access.multi (!) */
+  for(ss.traceId = 0; ss.traceId < TRACE_MAX; ++ss.traceId) {
+    if(TraceSetIsMember(space->busyTraces, ss.traceId)) {
+      ss.condemned = space->trace[ss.traceId].condemned;
+      res = MRGGroupScan(&ss, group, mrg);
+      AVER(res == ResOK);       /* impl.c.amc.access.error (!) */
+    }
+  }
+}
+
+static PoolClassStruct PoolClassMRGStruct = {
+  PoolClassSig,                         /* sig */
+  "MRG",                                /* name */
+  sizeof(MRGStruct),                    /* size */
+  offsetof(MRGStruct, poolStruct),      /* offset */
+  AttrSCAN | AttrALLOC | AttrFREE | AttrINCR_RB,
+  MRGInit,                              /* init */
+  MRGFinish,                            /* finish */
+  MRGAlloc,                             /* alloc */
+  MRGFree,                              /* free */
+  PoolNoBufferInit,                     /* bufferInit */
+  PoolNoBufferFinish,                   /* bufferFinish */
+  PoolNoBufferFill,                     /* bufferFill */
+  PoolNoBufferTrip,                     /* bufferTrip */
+  PoolNoBufferExpose,                   /* bufferExpose */
+  PoolNoBufferCover,                    /* bufferCover */
+  PoolNoCondemn,                        /* condemn */
+  MRGGrey,                              /* grey */
+  MRGScan,                              /* scan */
+  PoolNoFix,                            /* fix */
+  PoolNoReclaim,                        /* reclaim */
+  MRGAccess,                            /* access */
+  MRGDescribe,                          /* describe */
+  PoolClassSig                          /* impl.h.mpmst.class.end-sig */
+};
+
+PoolClass PoolClassMRG(void)
+{
+  return &PoolClassMRGStruct;
+}
+
+/* .check.norecurse: the expression &mrg->poolStruct is used instead of
+ * the more natural MRGPool(mrg).  The latter results in infinite
+ * recursion because MRGPool calls MRGCheck.
+ */
+static Bool MRGCheck(MRG mrg)
+{
+  Space space;
+
+  CHECKS(MRG, mrg);
+  CHECKD(Pool, &mrg->poolStruct);
+  CHECKL(mrg->poolStruct.class == &PoolClassMRGStruct);
+  CHECKL(RingCheck(&mrg->entry));
+  CHECKL(RingCheck(&mrg->exit));
+  CHECKL(RingCheck(&mrg->free));
+  CHECKL(RingCheck(&mrg->group));
+  space = PoolSpace(&mrg->poolStruct);  /* .check.norecurse */
+  CHECKL(mrg->extendBy == ArenaAlign(space));
+  return TRUE;
+}
diff --git a/mps/src/poolmrg.h b/mps/src/poolmrg.h
new file mode 100644
index 00000000000..d4411d5b2d0
--- /dev/null
+++ b/mps/src/poolmrg.h
@@ -0,0 +1,18 @@
+/*  impl.h.amc  draft impl
+ *
+ *               MANUAL RANK GUARDIAN POOL CLASS
+ *
+ *  $HopeName$
+ *  Copyright (C) 1995,1997 Harlequin Group, all rights reserved
+ */
+
+#ifndef poolmrg_h
+#define poolmrg_h
+
+#include "mpm.h"
+
+typedef struct MRGStruct *MRG;
+
+extern PoolClass PoolClassMRG(void);
+
+#endif /* poolmrg_h */