diff --git a/src/runtime/c/pgf/data.cxx b/src/runtime/c/pgf/data.cxx
index faaf916b6..9ec6eb9e3 100644
--- a/src/runtime/c/pgf/data.cxx
+++ b/src/runtime/c/pgf/data.cxx
@@ -39,6 +39,7 @@ void PgfConcr::release(ref<PgfConcr> concr)
     namespace_release(concr->cflags);
     namespace_release(concr->lins);
     namespace_release(concr->lincats);
+    phrasetable_release(concr->phrasetable);
     namespace_release(concr->printnames);
     PgfDB::free(concr);
 }
@@ -113,6 +114,11 @@ void PgfSequence::release(ref<PgfSequence> seq)
     PgfDB::free(seq);
 }
 
+void PgfSequenceBackrefs::release(ref<PgfSequenceBackrefs> backrefs)
+{
+    PgfDB::free(backrefs);
+}
+
 void PgfConcrLin::release(ref<PgfConcrLin> lin)
 {
     for (size_t i = 0; i < lin->args->len; i++) {
diff --git a/src/runtime/c/pgf/data.h b/src/runtime/c/pgf/data.h
index fe5adf4c4..40f3e1b92 100644
--- a/src/runtime/c/pgf/data.h
+++ b/src/runtime/c/pgf/data.h
@@ -141,6 +141,19 @@ struct PGF_INTERNAL_DECL PgfSequence {
     static void release(ref<PgfSequence> lincat);
 };
 
+struct PGF_INTERNAL_DECL PgfSequenceBackref {
+    object container;
+    size_t seq_index;
+};
+
+struct PGF_INTERNAL_DECL PgfSequenceBackrefs {
+    size_t ref_count;
+    Vector<PgfSequenceBackref> list;
+
+    static
+    void release(ref<PgfSequenceBackrefs> backrefs);
+};
+
 struct PGF_INTERNAL_DECL PgfSymbolCat {
     static const uint8_t tag = 0;
     size_t d;
@@ -206,6 +219,8 @@ PGF_INTERNAL_DECL
 void pgf_symbol_free(PgfSymbol sym);
 
 struct PGF_INTERNAL_DECL PgfConcrLincat {
+    static const uint8_t tag = 0;
+
     size_t ref_count;
 
     ref<PgfAbsCat> abscat;
@@ -223,6 +238,8 @@ struct PGF_INTERNAL_DECL PgfConcrLincat {
 };
 
 struct PGF_INTERNAL_DECL PgfConcrLin {
+    static const uint8_t tag = 1;
+
     size_t ref_count;
 
     ref<PgfAbsFun> absfun;
diff --git a/src/runtime/c/pgf/namespace.h b/src/runtime/c/pgf/namespace.h
index 0bb1d7824..41cabf429 100644
--- a/src/runtime/c/pgf/namespace.h
+++ b/src/runtime/c/pgf/namespace.h
@@ -20,7 +20,7 @@ template <class V>
 class Node;
 
 template <class V>
-using Namespace = ref<Node<V>>;
+using Namespace = ref<Node<ref<V>>>;
 
 template <class V>
 class PGF_INTERNAL_DECL Node
@@ -29,12 +29,12 @@ public:
     size_t ref_count;
 
     size_t sz;
-    ref<V> value;
+    V value;
     ref<Node> left;
     ref<Node> right;
 
     static
-    ref<Node> new_node(ref<V> value)
+    ref<Node> new_node(V value)
     {
         ref<Node> node = current_db->malloc<Node>();
         node->ref_count = 1;
@@ -50,11 +50,11 @@ public:
     }
 
     static
-    ref<Node> new_node(ref<V> value, ref<Node> left, ref<Node> right)
+    ref<Node> new_node(V value, ref<Node> left, ref<Node> right)
     {
         ref<Node> node = current_db->malloc<Node>();
         node->ref_count = 1;
-        node->sz        = 1+namespace_size(left)+namespace_size(right);
+        node->sz        = 1+Node::size(left)+Node::size(right);
         node->value     = value;
         node->left      = left;
         node->right     = right;
@@ -74,8 +74,17 @@ public:
 #endif
     }
 
-    static
-    void add_value_ref(ref<V> value)
+    template <class A> static
+    void add_value_ref(A &value)
+    {
+        value.add_ref();
+#ifdef DEBUG_NAMESPACE
+        printf("add_ref value %5ld %s (ref_count=%ld)\n", value.as_object(), value->name.text, value->ref_count);
+#endif
+    }
+
+    template <class A> static
+    void add_value_ref(ref<A> value)
     {
         value->ref_count++;
 #ifdef DEBUG_NAMESPACE
@@ -83,12 +92,34 @@ public:
 #endif
     }
 
+    template <class A> static
+    void release_value_ref(A &value)
+    {
+#ifdef DEBUG_NAMESPACE
+        printf("release value %5ld %s (ref_count=%ld)\n", value.as_object(), value->name.text, value->ref_count-1);
+#endif
+
+        value.release_ref();
+    }
+
+    template <class A> static
+    void release_value_ref(ref<A> value)
+    {
+#ifdef DEBUG_NAMESPACE
+        printf("release value %5ld %s (ref_count=%ld)\n", value.as_object(), value->name.text, value->ref_count-1);
+#endif
+
+        if (!(--value->ref_count)) {
+            A::release(value);
+        }
+    }
+
     static
-    ref<Node> balanceL(ref<V> value, ref<Node> left, ref<Node> right)
+    ref<Node> balanceL(V value, ref<Node> left, ref<Node> right)
     {
         if (right == 0) {
             if (left == 0) {
-                value->ref_count++;
+                add_value_ref(value);
                 return new_node(value);
             } else {
                 if (left->left == 0) {
@@ -100,8 +131,8 @@ public:
                         add_value_ref(value);
                         add_value_ref(left->value);
                         add_value_ref(left->right->value);
-                        Namespace<V> new_left  = new_node(left->value);
-                        Namespace<V> new_right = new_node(value);
+                        ref<Node<V>> new_left  = new_node(left->value);
+                        ref<Node<V>> new_right = new_node(value);
                         return new_node(left->right->value,
                                         new_left,
                                         new_right);
@@ -109,7 +140,7 @@ public:
                 } else {
                     if (left->right == 0) {
                         add_value_ref(value);
-                        Namespace<V> new_right = new_node(value);
+                        ref<Node<V>> new_right = new_node(value);
                         add_value_ref(left->value);
                         add_node_ref(left->left);
                         return new_node(left->value,
@@ -121,7 +152,7 @@ public:
                             add_value_ref(left->value);
                             add_node_ref(left->left);
                             add_node_ref(left->right);
-                            Namespace<V> new_right =
+                            ref<Node<V>> new_right =
                                 new_node(value,
                                          left->right,
                                          0);
@@ -137,11 +168,11 @@ public:
                                 add_node_ref(left->right->left);
                             if (left->right->right != 0)
                                 add_node_ref(left->right->right);
-                            Namespace<V> new_left  =
+                            ref<Node<V>> new_left  =
                                 new_node(left->value,
                                          left->left,
                                          left->right->left);
-                            Namespace<V> new_right =
+                            ref<Node<V>> new_right =
                                 new_node(value,
                                          left->right->right,
                                          0);
@@ -165,7 +196,7 @@ public:
                         add_node_ref(left->left);
                         add_node_ref(left->right);
                         add_node_ref(right);
-                        Namespace<V> new_right =
+                        ref<Node<V>> new_right =
                             new_node(value,
                                      left->right,
                                      right);
@@ -182,11 +213,11 @@ public:
                         if (left->right->right != 0)
                             add_node_ref(left->right->right);
                         add_node_ref(right);
-                        Namespace<V> new_left =
+                        ref<Node<V>> new_left =
                             new_node(left->value,
                                      left->left,
                                      left->right->left);
-                        Namespace<V> new_right =
+                        ref<Node<V>> new_right =
                             new_node(value,
                                      left->right->right,
                                      right);
@@ -205,7 +236,7 @@ public:
     }
 
     static
-    ref<Node> balanceR(ref<V> value, ref<Node> left, ref<Node> right)
+    ref<Node> balanceR(V value, ref<Node> left, ref<Node> right)
     {
         if (left == 0) {
             if (right == 0) {
@@ -221,7 +252,7 @@ public:
                         add_value_ref(value);
                         add_value_ref(right->value);
                         add_node_ref(right->right);
-                        Namespace<V> new_left =
+                        ref<Node<V>> new_left =
                             new_node(value);
                         return new_node(right->value,
                                         new_left,
@@ -232,9 +263,9 @@ public:
                         add_value_ref(value);
                         add_value_ref(right->value);
                         add_value_ref(right->left->value);
-                        Namespace<V> new_left =
+                        ref<Node<V>> new_left =
                             new_node(value);
-                        Namespace<V> new_right =
+                        ref<Node<V>> new_right =
                             new_node(right->value);
                         return new_node(right->left->value,
                                         new_left,
@@ -245,7 +276,7 @@ public:
                             add_value_ref(right->value);
                             add_node_ref(right->left);
                             add_node_ref(right->right);
-                            Namespace<V> new_left =
+                            ref<Node<V>> new_left =
                                 new_node(value,
                                          0,
                                          right->left);
@@ -261,11 +292,11 @@ public:
                             if (right->left->right != 0)
                                 add_node_ref(right->left->right);
                             add_node_ref(right->right);
-                            Namespace<V> new_left =
+                            ref<Node<V>> new_left =
                                 new_node(value,
                                          0,
                                          right->left->left);
-                            Namespace<V> new_right =
+                            ref<Node<V>> new_right =
                                 new_node(right->value,
                                          right->left->right,
                                          right->right);
@@ -289,7 +320,7 @@ public:
                         add_node_ref(left);
                         add_node_ref(right->left);
                         add_node_ref(right->right);
-                        Namespace<V> new_left =
+                        ref<Node<V>> new_left =
                             new_node(value,
                                      left,
                                      right->left);
@@ -306,11 +337,11 @@ public:
                         if (right->left->right != 0)
                             add_node_ref(right->left->right);
                         add_node_ref(right->right);
-                        Namespace<V> new_left =
+                        ref<Node<V>> new_left =
                             new_node(value,
                                      left,
                                      right->left->left);
-                        Namespace<V> new_right =
+                        ref<Node<V>> new_right =
                             new_node(right->value,
                                      right->left->right,
                                      right->right);
@@ -327,6 +358,68 @@ public:
             }
         }
     }
+
+    static
+    size_t size(ref<Node> node)
+    {
+        if (node == 0)
+            return 0;
+        return node->sz;
+    }
+
+    static
+    ref<Node> pop_first(ref<Node> node, V *res)
+    {
+        if (node == 0) {
+            return 0;
+        } else if (node->left == 0) {
+            *res = node->value;
+            if (node->right != 0)
+                node->right->ref_count++;
+            return node->right;
+        } else {
+            ref<Node> new_left = pop_first(node->left, res);
+            ref<Node> new_node = balanceR(node->value, new_left, node->right);
+            release(new_left);
+            return new_node;
+        }
+    }
+
+    static
+    ref<Node> pop_last(ref<Node> node, V *res)
+    {
+        if (node == 0) {
+            return 0;
+        } else if (node->right == 0) {
+            *res = node->value;
+            if (node->left != 0)
+                node->left->ref_count++;
+            return node->left;
+        } else {
+            ref<Node> new_right = pop_last(node->right, res);
+            ref<Node> new_node = balanceR(node->value, node->left, new_right);
+            release(new_right);
+            return new_node;
+        }
+    }
+
+    static
+    void release(ref<Node> node)
+    {
+        if (node == 0)
+            return;
+
+#ifdef DEBUG_NAMESPACE
+        printf("release node %6ld %s (ref_count=%ld)\n", node.as_object(), node->value->name.text, node->ref_count-1);
+#endif
+
+        if (!(--node->ref_count)) {
+            release(node->left);
+            release(node->right);
+            release_value_ref(node->value);
+            PgfDB::free(node);
+        }
+    }
 };
 
 template <class V>
@@ -345,17 +438,17 @@ template <class V>
 Namespace<V> namespace_insert(Namespace<V> map, ref<V> value)
 {
     if (map == 0)
-        return Node<V>::new_node(value);
+        return Node<ref<V>>::new_node(value);
 
     int cmp = textcmp(&value->name,&map->value->name);
     if (cmp < 0) {
         Namespace<V> left = namespace_insert(map->left, value);
-        Namespace<V> node = Node<V>::balanceL(map->value,left,map->right);
+        Namespace<V> node = Node<ref<V>>::balanceL(map->value,left,map->right);
         namespace_release(left);
         return node;
     } else if (cmp > 0) {
         Namespace<V> right = namespace_insert(map->right, value);
-        Namespace<V> node  = Node<V>::balanceR(map->value, map->left, right);
+        Namespace<V> node  = Node<ref<V>>::balanceR(map->value, map->left, right);
         namespace_release(right);
         return node;
     } else {
@@ -363,32 +456,37 @@ Namespace<V> namespace_insert(Namespace<V> map, ref<V> value)
             map->left->ref_count++;
         if (map->right != 0)
             map->right->ref_count++;
-        return Node<V>::new_node(value,map->left,map->right);
+        return Node<ref<V>>::new_node(value,map->left,map->right);
     }
 }
 
 template <class V>
-Namespace<V> namespace_delete(Namespace<V> map, PgfText* name)
+Namespace<V> namespace_delete(Namespace<V> map, PgfText* name,
+                              ref<V> *pvalue = NULL)
 {
-    if (map == 0)
+    if (map == 0) {
+        if (pvalue != NULL) *pvalue = 0;
         return 0;
+    }
 
     int cmp = textcmp(name,&map->value->name);
     if (cmp < 0) {
-        Namespace<V> left = namespace_delete(map->left, name);
+        Namespace<V> left = namespace_delete(map->left, name, pvalue);
         if (left == map->left)
             return map;
-        Namespace<V> node = Node<V>::balanceR(map->value,left,map->right);
+        Namespace<V> node = Node<ref<V>>::balanceR(map->value,left,map->right);
         namespace_release(left);
         return node;
     } else if (cmp > 0) {
-        Namespace<V> right = namespace_delete(map->right, name);
+        Namespace<V> right = namespace_delete(map->right, name, pvalue);
         if (right == map->right)
             return map;
-        Namespace<V> node  = Node<V>::balanceL(map->value,map->left,right);
+        Namespace<V> node  = Node<ref<V>>::balanceL(map->value,map->left,right);
         namespace_release(right);
         return node;
     } else {
+        if (pvalue != NULL) *pvalue = map->value;
+
         if (map->left == 0) {
             if (map->right != 0)
                 map->right->ref_count++;
@@ -399,54 +497,20 @@ Namespace<V> namespace_delete(Namespace<V> map, PgfText* name)
             return map->left;
         } else if (map->left->sz > map->right->sz) {
             ref<V> value;
-            Namespace<V> new_left = namespace_pop_last(map->left, &value);
-            Namespace<V> node = Node<V>::balanceR(value, new_left, map->right);
+            Namespace<V> new_left = Node<ref<V>>::pop_last(map->left, &value);
+            Namespace<V> node = Node<ref<V>>::balanceR(value, new_left, map->right);
             namespace_release(new_left);
             return node;
         } else {
             ref<V> value;
-            Namespace<V> new_right = namespace_pop_first(map->right, &value);
-            Namespace<V> node = Node<V>::balanceL(value, map->left, new_right);
+            Namespace<V> new_right = Node<ref<V>>::pop_first(map->right, &value);
+            Namespace<V> node = Node<ref<V>>::balanceL(value, map->left, new_right);
             namespace_release(new_right);
             return node;
         }
     }
 }
 
-template <class V>
-Namespace<V> namespace_pop_first(Namespace<V> map, ref<V> *res)
-{
-    if (map == 0) {
-        return 0;
-    } else if (map->left == 0) {
-        *res = map->value;
-        if (map->right != 0)
-            map->right->ref_count++;
-        return map->right;
-    } else {
-        Namespace<V> new_left = namespace_pop_first(map->left, res);
-        Namespace<V> node = Node<V>::balanceR(map->value, new_left, map->right);
-        namespace_release(new_left);
-        return node;
-    }
-}
-
-template <class V>
-Namespace<V> namespace_pop_last(Namespace<V> map, ref<V> *res)
-{
-    if (map == 0) {
-        return 0;
-    } else if (map->right == 0) {
-        *res = map->value;
-        if (map->left != 0)
-            map->left->ref_count++;
-        return map->left;
-    } else {
-        Namespace<V> new_right = namespace_pop_last(map->right, res);
-        return Node<V>::balanceR(map->value, map->left, new_right);
-    }
-}
-
 template <class V>
 ref<V> namespace_lookup(Namespace<V> map, PgfText *name)
 {
@@ -465,9 +529,7 @@ ref<V> namespace_lookup(Namespace<V> map, PgfText *name)
 template <class V>
 size_t namespace_size(Namespace<V> map)
 {
-    if (map == 0)
-        return 0;
-    return map->sz;
+    return Node<ref<V>>::size(map);
 }
 
 template <class V>
@@ -492,27 +554,7 @@ void namespace_iter(Namespace<V> map, PgfItor* itor, PgfExn *err)
 template <class V>
 void namespace_release(Namespace<V> node)
 {
-    if (node == 0)
-        return;
-
-#ifdef DEBUG_NAMESPACE
-    printf("release node %6ld %s (ref_count=%ld)\n", node.as_object(), node->value->name.text, node->ref_count-1);
-#endif
-
-    if (!(--node->ref_count)) {
-        namespace_release(node->left);
-        namespace_release(node->right);
-
-#ifdef DEBUG_NAMESPACE
-        printf("release value %5ld %s (ref_count=%ld)\n", node->value.as_object(), node->value->name.text, node->value->ref_count-1);
-#endif
-
-        if (!(--node->value->ref_count)) {
-            V::release(node->value);
-        }
-
-        PgfDB::free(node);
-    }
+    Node<ref<V>>::release(node);
 }
 
 #endif
diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index b176b1cee..c629d28fa 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -147,7 +147,7 @@ PgfDB *pgf_read_ngf(const char *fpath,
 			db->cleanup_revisions();
 
             ref<PgfPGF> pgf = PgfDB::get_revision(master);
-            Node<PgfPGF>::add_value_ref(pgf);
+            Node<ref<PgfPGF>>::add_value_ref(pgf);
             *revision = pgf.as_object();
         }
 
@@ -828,16 +828,18 @@ void pgf_iter_lins(PgfDB *db, PgfConcrRevision cnc_revision,
 
 PGF_API
 PgfPhrasetableIds *pgf_iter_sequences(PgfDB *db, PgfConcrRevision cnc_revision,
-                                      PgfSequenceItor *itor, PgfExn *err)
+                                      PgfSequenceItor *itor,
+                                      PgfMorphoCallback *callback,
+                                      PgfExn *err)
 {
     PGF_API_BEGIN {
         DB_scope scope(db, READER_SCOPE);
         ref<PgfConcr> concr = PgfDB::revision2concr(cnc_revision);
 
-		PgfPhrasetableIds *seq_ids = new PgfPhrasetableIds();
-		seq_ids->start(concr);
+        PgfPhrasetableIds *seq_ids = new PgfPhrasetableIds();
+        seq_ids->start(concr);
 
-        phrasetable_iter(concr->phrasetable, itor, seq_ids, err);
+        phrasetable_iter(concr, concr->phrasetable, itor, callback, seq_ids, err);
 
         return seq_ids;
     } PGF_API_END
@@ -1108,25 +1110,25 @@ PgfRevision pgf_clone_revision(PgfDB *db, PgfRevision revision,
 
         new_pgf->gflags = pgf->gflags;
         if (pgf->gflags != 0)
-            Node<PgfFlag>::add_node_ref(pgf->gflags);
+            Node<ref<PgfFlag>>::add_node_ref(pgf->gflags);
 
         new_pgf->abstract.name = textdup_db(&(*pgf->abstract.name));
 
         new_pgf->abstract.aflags = pgf->abstract.aflags;
         if (pgf->abstract.aflags != 0)
-            Node<PgfFlag>::add_node_ref(pgf->abstract.aflags);
+            Node<ref<PgfFlag>>::add_node_ref(pgf->abstract.aflags);
 
         new_pgf->abstract.funs = pgf->abstract.funs;
         if (pgf->abstract.funs != 0)
-            Node<PgfAbsFun>::add_node_ref(pgf->abstract.funs);
+            Node<ref<PgfAbsFun>>::add_node_ref(pgf->abstract.funs);
 
         new_pgf->abstract.cats = pgf->abstract.cats;
         if (pgf->abstract.cats != 0)
-            Node<PgfAbsCat>::add_node_ref(pgf->abstract.cats);
+            Node<ref<PgfAbsCat>>::add_node_ref(pgf->abstract.cats);
 
         new_pgf->concretes = pgf->concretes;
         if (pgf->concretes != 0)
-            Node<PgfConcr>::add_node_ref(pgf->concretes);
+            Node<ref<PgfConcr>>::add_node_ref(pgf->concretes);
 
         new_pgf->prev = 0;
         new_pgf->next = 0;
@@ -1170,7 +1172,7 @@ PgfRevision pgf_checkout_revision(PgfDB *db, PgfText *name,
         DB_scope scope(db, WRITER_SCOPE);
         ref<PgfPGF> pgf = PgfDB::get_revision(name);
         if (pgf != 0) {
-            Node<PgfPGF>::add_value_ref(pgf);
+            Node<ref<PgfPGF>>::add_value_ref(pgf);
             db->ref_count++;
         }
         return pgf.as_object();
@@ -1335,27 +1337,28 @@ PgfConcrRevision pgf_clone_concrete(PgfDB *db, PgfRevision revision,
 
         clone->cflags = concr->cflags;
 		if (clone->cflags != 0)
-            Node<PgfFlag>::add_node_ref(clone->cflags);
+            Node<ref<PgfFlag>>::add_node_ref(clone->cflags);
 
         clone->lins = concr->lins;
 		if (clone->lins != 0)
-            Node<PgfConcrLin>::add_node_ref(clone->lins);
+            Node<ref<PgfConcrLin>>::add_node_ref(clone->lins);
 
         clone->lincats = concr->lincats;
 		if (clone->lincats != 0)
-            Node<PgfConcrLincat>::add_node_ref(clone->lincats);
+            Node<ref<PgfConcrLincat>>::add_node_ref(clone->lincats);
+
+        clone->phrasetable = concr->phrasetable;
+		if (clone->phrasetable != 0)
+            Node<PgfPhrasetableEntry>::add_node_ref(clone->phrasetable);
 
         clone->printnames = concr->printnames;
 		if (clone->printnames != 0)
-            Node<PgfConcrPrintname>::add_node_ref(clone->printnames);
+            Node<ref<PgfConcrPrintname>>::add_node_ref(clone->printnames);
 
         clone->prev = 0;
         clone->next = 0;
         memcpy(&clone->name, name, sizeof(PgfText)+name->size+1);
 
-        if (clone->cflags != 0)
-            Node<PgfFlag>::add_node_ref(clone->cflags);
-
         PgfDB::link_transient_revision(clone);
 
         Namespace<PgfConcr> concrs =
@@ -1394,6 +1397,8 @@ class PGF_INTERNAL PgfLinBuilder : public PgfLinBuilderIface
     ref<Vector<ref<PgfPResult>>> res;
     ref<Vector<ref<PgfSequence>>> seqs;
 
+    object container; // what are we building?
+
     size_t var_index;
     size_t arg_index;
     size_t res_index;
@@ -1459,6 +1464,8 @@ public:
         lincat->fields = db_fields;
         lincat->n_lindefs = n_lindefs;
 
+        this->container = ref<PgfConcrLincat>::tagged(lincat);
+
         build->build(this, err);
         if (err->type == PGF_EXN_NONE && res_index != res->len) {
             err->type = PGF_EXN_PGF_ERROR;
@@ -1500,6 +1507,8 @@ public:
         lin->res  = res;
         lin->seqs = seqs;
 
+        this->container = ref<PgfConcrLin>::tagged(lin);
+
         build->build(this, err);
         if (err->type == PGF_EXN_NONE && res_index != res->len) {
             err->type = PGF_EXN_PGF_ERROR;
@@ -1892,13 +1901,12 @@ public:
                 throw pgf_error(builder_error_msg);
 
             PgfPhrasetable phrasetable =
-				phrasetable_internalize(concr->phrasetable, &seq);
-			if (phrasetable != concr->phrasetable) {
-				phrasetable_release(concr->phrasetable);
-				concr->phrasetable = phrasetable;
-			} else {
-				*vector_elem(seqs, seq_index) = seq;
-			}
+				phrasetable_internalize(concr->phrasetable,
+                                        container, seq_index,
+                                        &seq);
+            phrasetable_release(concr->phrasetable);
+            concr->phrasetable = phrasetable;
+            *vector_elem(seqs, seq_index) = seq;
 
 			res = seq;
 
@@ -1919,7 +1927,17 @@ public:
             if (seq_index >= seqs->len)
                 throw pgf_error(builder_error_msg);
 
-            *vector_elem(seqs, seq_index) = seq_id;
+            ref<PgfSequence> seq = seq_id;
+            seq->ref_count++;
+
+            PgfPhrasetable phrasetable =
+				phrasetable_internalize(concr->phrasetable,
+                                        container, seq_index,
+                                        &seq);
+            phrasetable_release(concr->phrasetable);
+            concr->phrasetable = phrasetable;
+            *vector_elem(seqs, seq_index) = seq;
+
             seq_index++;
         } PGF_API_END
 	}
@@ -2055,8 +2073,19 @@ void pgf_drop_lincat(PgfDB *db,
 
         ref<PgfConcr> concr = PgfDB::revision2concr(revision);
 
+        ref<PgfConcrLincat> lincat;
         Namespace<PgfConcrLincat> lincats =
-            namespace_delete(concr->lincats, name);
+            namespace_delete(concr->lincats, name, &lincat);
+        if (lincat != 0) {
+            object container = ref<PgfConcrLincat>::tagged(lincat);
+            for (size_t i = 0; i < lincat->seqs->len; i++) {
+                ref<PgfSequence> seq = *vector_elem(lincat->seqs, i);
+                PgfPhrasetable new_phrasetable =
+                    phrasetable_delete(concr->phrasetable,container,i,seq);
+                phrasetable_release(concr->phrasetable);
+                concr->phrasetable = new_phrasetable;
+            }
+        }
         namespace_release(concr->lincats);
         concr->lincats = lincats;
     } PGF_API_END
@@ -2105,8 +2134,19 @@ void pgf_drop_lin(PgfDB *db,
 
         ref<PgfConcr> concr = PgfDB::revision2concr(revision);
 
+        ref<PgfConcrLin> lin;
         Namespace<PgfConcrLin> lins =
-            namespace_delete(concr->lins, name);
+            namespace_delete(concr->lins, name, &lin);
+        if (lin != 0) {
+            object container = ref<PgfConcrLin>::tagged(lin);
+            for (size_t i = 0; i < lin->seqs->len; i++) {
+                ref<PgfSequence> seq = *vector_elem(lin->seqs, i);
+                PgfPhrasetable new_phrasetable =
+                    phrasetable_delete(concr->phrasetable,container,i,seq);
+                phrasetable_release(concr->phrasetable);
+                concr->phrasetable = new_phrasetable;
+            }
+        }
         namespace_release(concr->lins);
         concr->lins = lins;
     } PGF_API_END
diff --git a/src/runtime/c/pgf/pgf.h b/src/runtime/c/pgf/pgf.h
index 850f858a9..f04d456fa 100644
--- a/src/runtime/c/pgf/pgf.h
+++ b/src/runtime/c/pgf/pgf.h
@@ -400,12 +400,21 @@ typedef struct PgfPhrasetableIds PgfPhrasetableIds;
 
 typedef struct PgfSequenceItor PgfSequenceItor;
 struct PgfSequenceItor {
-	void (*fn)(PgfSequenceItor* self, size_t seq_id, object value, PgfExn *err);
+	int (*fn)(PgfSequenceItor* self, size_t seq_id, object value,
+              PgfExn *err);
 };
 
-PGF_API
+typedef struct PgfMorphoCallback PgfMorphoCallback;
+struct PgfMorphoCallback {
+	void (*fn)(PgfMorphoCallback* self, PgfText *lemma, PgfText *analysis, prob_t prob,
+	           PgfExn* err);
+};
+
+PGF_API_DECL
 PgfPhrasetableIds *pgf_iter_sequences(PgfDB *db, PgfConcrRevision cnc_revision,
-                                      PgfSequenceItor *itor, PgfExn *err);
+                                      PgfSequenceItor *itor,
+                                      PgfMorphoCallback *callback,
+                                      PgfExn *err);
 
 PGF_API_DECL
 void pgf_get_lincat_counts_internal(object o, size_t *counts);
diff --git a/src/runtime/c/pgf/phrasetable.cxx b/src/runtime/c/pgf/phrasetable.cxx
index 71f540680..d9aca46e7 100644
--- a/src/runtime/c/pgf/phrasetable.cxx
+++ b/src/runtime/c/pgf/phrasetable.cxx
@@ -11,7 +11,7 @@ PgfPhrasetableIds::PgfPhrasetableIds()
 void PgfPhrasetableIds::start(ref<PgfConcr> concr)
 {
 	next_id = 0;
-	n_pairs = namespace_size(concr->phrasetable);
+	n_pairs = phrasetable_size(concr->phrasetable);
 	size_t mem_size = sizeof(SeqIdPair)*n_pairs;
 	pairs = (SeqIdPair*) malloc(mem_size);
 	if (pairs == NULL)
@@ -72,6 +72,24 @@ void PgfPhrasetableIds::end()
 	pairs = NULL;
 }
 
+void PgfPhrasetableEntry::add_ref()
+{
+    seq->ref_count++;
+    if (backrefs != 0)
+        backrefs->ref_count++;
+}
+
+void PgfPhrasetableEntry::release_ref()
+{
+    if (!(--seq->ref_count)) {
+        PgfSequence::release(seq);
+    }
+
+    if (backrefs != 0 && !(--backrefs->ref_count)) {
+        PgfSequenceBackrefs::release(backrefs);
+    }
+}
+
 static
 int lparam_cmp(PgfLParam *p1, PgfLParam *p2)
 {
@@ -228,55 +246,97 @@ int sequence_cmp(ref<PgfSequence> seq1, ref<PgfSequence> seq2)
 }
 
 PGF_INTERNAL
-PgfPhrasetable phrasetable_internalize(PgfPhrasetable table, ref<PgfSequence> *pseq)
+PgfPhrasetable phrasetable_internalize(PgfPhrasetable table,
+                                       object container,
+                                       size_t seq_index,
+                                       ref<PgfSequence> *pseq)
 {
     if (table == 0) {
-		PgfPhrasetable table = Node<PgfSequence>::new_node(*pseq);
-		Node<PgfSequence>::add_value_ref(table->value);
-        return table;
+        PgfPhrasetableEntry entry;
+        entry.seq = *pseq;
+        entry.backrefs = PgfDB::malloc<PgfSequenceBackrefs>(sizeof(PgfSequenceBackref));
+        entry.backrefs->ref_count = 1;
+        entry.backrefs->list.len = 1;
+        entry.backrefs->list.data[0].container = container;
+        entry.backrefs->list.data[0].seq_index = seq_index;
+        entry.seq->ref_count++;
+        return Node<PgfPhrasetableEntry>::new_node(entry);
 	}
 
-    int cmp = sequence_cmp(*pseq,table->value);
+    int cmp = sequence_cmp(*pseq,table->value.seq);
     if (cmp < 0) {
-        PgfPhrasetable left = phrasetable_internalize(table->left, pseq);
-        if (left == table->left)
-			return table;
-		else {
-			PgfPhrasetable node = Node<PgfSequence>::balanceL(table->value,left,table->right);
-			namespace_release(left);
-			return node;
-		}
+        PgfPhrasetable left = phrasetable_internalize(table->left,
+                                                      container,
+                                                      seq_index,
+                                                      pseq);
+        PgfPhrasetable node = Node<PgfPhrasetableEntry>::balanceL(table->value,left,table->right);
+        phrasetable_release(left);
+        return node;
     } else if (cmp > 0) {
-        PgfPhrasetable right = phrasetable_internalize(table->right, pseq);
-        if (right == table->right)
-			return table;
-		else {
-			PgfPhrasetable node  = Node<PgfSequence>::balanceR(table->value, table->left, right);
-			phrasetable_release(right);
-			return node;
-		}
+        PgfPhrasetable right = phrasetable_internalize(table->right,
+                                                       container,
+                                                       seq_index,
+                                                       pseq);
+        PgfPhrasetable node  = Node<PgfPhrasetableEntry>::balanceR(table->value, table->left, right);
+        phrasetable_release(right);
+        return node;
     } else {
 		if (!(--(*pseq)->ref_count)) {
             PgfSequence::release(*pseq);
         }
 
-		Node<PgfSequence>::add_value_ref(table->value);
+		table->value.seq->ref_count++;
+		*pseq = table->value.seq;
 
-		*pseq = table->value;
-        return table;
-    }
+        if (table->left != 0)
+            table->left->ref_count++;
+        if (table->right != 0)
+            table->right->ref_count++;
+
+        size_t len = (table->value.backrefs)
+                         ? table->value.backrefs->list.len
+                         : 0;
+        PgfPhrasetableEntry entry;
+        entry.seq = table->value.seq;
+        entry.backrefs = PgfDB::malloc<PgfSequenceBackrefs>((len+1)*sizeof(PgfSequenceBackref));
+        entry.backrefs->ref_count = 1;
+        entry.backrefs->list.len = len+1;
+        memcpy(entry.backrefs->list.data, table->value.backrefs->list.data, len*sizeof(PgfSequenceBackref));
+        entry.backrefs->list.data[len].container = container;
+        entry.backrefs->list.data[len].seq_index = seq_index;
+        entry.seq->ref_count++;
+        return Node<PgfPhrasetableEntry>::new_node(entry,table->left,table->right);
+     }
 }
 
 PGF_INTERNAL_DECL
-ref<PgfSequence> phrasetable_get(PgfPhrasetable table, size_t seq_id)
+ref<PgfSequence> phrasetable_relink(PgfPhrasetable table,
+                                    object container,
+                                    size_t seq_index,
+                                    size_t seq_id)
 {
 	while (table != 0) {
 		size_t left_sz = table->left->sz;
 		if (seq_id < left_sz)
 			table = table->left;
-		else if (seq_id == left_sz)
-			return table->value;
-		else {
+		else if (seq_id == left_sz) {
+            size_t len = (table->value.backrefs)
+                             ? table->value.backrefs->list.len
+                             : 0;
+
+            ref<PgfSequenceBackrefs> backrefs =
+                PgfDB::malloc<PgfSequenceBackrefs>((len+1)*sizeof(PgfSequenceBackref));
+            backrefs->ref_count = 1;
+            backrefs->list.len = len+1;
+            memcpy(backrefs->list.data, table->value.backrefs->list.data, len*sizeof(PgfSequenceBackref));
+            backrefs->list.data[len].container = container;
+            backrefs->list.data[len].seq_index = seq_index;
+            if (table->value.backrefs != 0)
+                PgfSequenceBackrefs::release(table->value.backrefs);
+            table->value.backrefs = backrefs;
+
+			return table->value.seq;
+        } else {
 			table = table->right;
 			seq_id -= left_sz+1;
 		}
@@ -284,23 +344,140 @@ ref<PgfSequence> phrasetable_get(PgfPhrasetable table, size_t seq_id)
 	return 0;
 }
 
+PgfPhrasetable phrasetable_delete(PgfPhrasetable table,
+                                  object container,
+                                  size_t seq_index,
+                                  ref<PgfSequence> seq)
+{
+    if (table == 0)
+        return 0;
+
+    int cmp = sequence_cmp(seq,table->value.seq);
+    if (cmp < 0) {
+        PgfPhrasetable left = phrasetable_delete(table->left,
+                                                 container, seq_index,
+                                                 seq);
+        if (left == table->left)
+            return table;
+        PgfPhrasetable node = Node<PgfPhrasetableEntry>::balanceR(table->value,left,table->right);
+        phrasetable_release(left);
+        return node;
+    } else if (cmp > 0) {
+        PgfPhrasetable right = phrasetable_delete(table->right, 
+                                                  container, seq_index,
+                                                  seq);
+        if (right == table->right)
+            return table;
+        PgfPhrasetable node  = Node<PgfPhrasetableEntry>::balanceL(table->value,table->left,right);
+        phrasetable_release(right);
+        return node;
+    } else {
+        PgfPhrasetableEntry entry;
+
+        size_t len = table->value.backrefs->list.len;
+        if (len > 1) {
+            entry.backrefs =
+                PgfDB::malloc<PgfSequenceBackrefs>((len-1)*sizeof(PgfSequenceBackref));
+            entry.backrefs->ref_count = 1;
+            entry.backrefs->list.len  = len-1;
+            size_t i = 0;
+            while (i < len) {
+                PgfSequenceBackref *backref = 
+                    vector_elem(&table->value.backrefs->list, i);
+                if (backref->container == container &&
+                    backref->seq_index == seq_index) {
+                    break;
+                }
+                *vector_elem(&entry.backrefs->list, i) = *backref;
+                i++;
+            }
+            i++;
+            while (i < len) {
+                PgfSequenceBackref *backref = 
+                    vector_elem(&table->value.backrefs->list, i);
+                *vector_elem(&entry.backrefs->list, i-1) = *backref;
+                i++;
+            }
+
+            entry.seq = table->value.seq;
+            table->value.seq->ref_count++;
+            return Node<PgfPhrasetableEntry>::new_node(entry, table->left, table->right);
+        } else {
+            if (table->left == 0) {
+                if (table->right != 0)
+                    table->right->ref_count++;
+                return table->right;
+            } else if (table->right == 0) {
+                if (table->left != 0)
+                    table->left->ref_count++;
+                return table->left;
+            } else if (table->left->sz > table->right->sz) {
+                PgfPhrasetable new_left = Node<PgfPhrasetableEntry>::pop_last(table->left, &entry);
+                PgfPhrasetable node = Node<PgfPhrasetableEntry>::balanceR(entry, new_left, table->right);
+                phrasetable_release(new_left);
+                return node;
+            } else {
+                PgfPhrasetable new_right = Node<PgfPhrasetableEntry>::pop_first(table->right, &entry);
+                PgfPhrasetable node = Node<PgfPhrasetableEntry>::balanceL(entry, table->left, new_right);
+                phrasetable_release(new_right);
+                return node;
+            }
+        }
+    }
+}
+
 PGF_INTERNAL
-void phrasetable_iter(PgfPhrasetable table, PgfSequenceItor* itor,
+size_t phrasetable_size(PgfPhrasetable table)
+{
+    return Node<PgfPhrasetableEntry>::size(table);
+}
+
+PGF_INTERNAL
+void phrasetable_iter(PgfConcr *concr,
+                      PgfPhrasetable table,
+                      PgfSequenceItor* itor,
+                      PgfMorphoCallback *callback,
                       PgfPhrasetableIds *seq_ids, PgfExn *err)
 {
     if (table == 0)
         return;
 
-    phrasetable_iter(table->left, itor, seq_ids, err);
+    phrasetable_iter(concr, table->left, itor, callback, seq_ids, err);
     if (err->type != PGF_EXN_NONE)
         return;
 
-	size_t seq_id = seq_ids->add(table->value);
-    itor->fn(itor, seq_id, table->value.as_object(), err);
+	size_t seq_id = seq_ids->add(table->value.seq);
+    int res = itor->fn(itor, seq_id, table->value.seq.as_object(), err);
     if (err->type != PGF_EXN_NONE)
         return;
 
-    phrasetable_iter(table->right, itor, seq_ids, err);
+    if (table->value.backrefs != 0 && res == 0 && callback != 0) {
+        for (size_t i = 0; i < table->value.backrefs->list.len; i++) {
+            PgfSequenceBackref backref = *vector_elem(&table->value.backrefs->list,i);
+            switch (ref<PgfConcrLin>::get_tag(backref.container)) {
+            case PgfConcrLin::tag: {
+                ref<PgfConcrLin> lin = ref<PgfConcrLin>::untagged(backref.container);
+                ref<PgfConcrLincat> lincat =
+                    namespace_lookup(concr->lincats, &lin->absfun->type->name);
+                if (lincat != 0) {
+                    ref<PgfText> field =
+                        *vector_elem(lincat->fields, backref.seq_index % lincat->fields->len);
+
+                    callback->fn(callback, &lin->absfun->name, &(*field), lincat->abscat->prob+lin->absfun->prob, err);
+                    if (err->type != PGF_EXN_NONE)
+                        return;
+                }
+                break;
+            }
+            case PgfConcrLincat::tag: {
+                //ignore
+                break;
+            }
+            }
+        }
+    }
+
+    phrasetable_iter(concr, table->right, itor, callback, seq_ids, err);
     if (err->type != PGF_EXN_NONE)
         return;
 }
@@ -308,5 +485,5 @@ void phrasetable_iter(PgfPhrasetable table, PgfSequenceItor* itor,
 PGF_INTERNAL
 void phrasetable_release(PgfPhrasetable table)
 {
-	namespace_release(table);
+    Node<PgfPhrasetableEntry>::release(table);
 }
diff --git a/src/runtime/c/pgf/phrasetable.h b/src/runtime/c/pgf/phrasetable.h
index bbfd7116b..987ba9d7f 100644
--- a/src/runtime/c/pgf/phrasetable.h
+++ b/src/runtime/c/pgf/phrasetable.h
@@ -1,9 +1,19 @@
 #ifndef PHRASETABLE_H
 #define PHRASETABLE_H
 
-class PgfSequence;
+struct PgfSequence;
+struct PgfSequenceBackrefs;
+
+struct PGF_INTERNAL_DECL PgfPhrasetableEntry {
+    ref<PgfSequence> seq;
+    ref<PgfSequenceBackrefs> backrefs;
+
+    void add_ref();
+    void release_ref();
+};
+
 class PgfSequenceItor;
-typedef ref<Node<PgfSequence>> PgfPhrasetable;
+typedef ref<Node<PgfPhrasetableEntry>> PgfPhrasetable;
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wattributes"
@@ -41,13 +51,30 @@ private:
 #pragma GCC diagnostic pop
 
 PGF_INTERNAL_DECL
-PgfPhrasetable phrasetable_internalize(PgfPhrasetable table, ref<PgfSequence> *seq);
+PgfPhrasetable phrasetable_internalize(PgfPhrasetable table,
+                                       object container,
+                                       size_t seq_index,
+                                       ref<PgfSequence> *seq);
 
 PGF_INTERNAL_DECL
-ref<PgfSequence> phrasetable_get(PgfPhrasetable table, size_t seq_id);
+ref<PgfSequence> phrasetable_relink(PgfPhrasetable table,
+                                    object container,
+                                    size_t seq_index,
+                                    size_t seq_id);
+
+PgfPhrasetable phrasetable_delete(PgfPhrasetable table,
+                                  object container,
+                                  size_t seq_index,
+                                  ref<PgfSequence> seq);
 
 PGF_INTERNAL_DECL
-void phrasetable_iter(PgfPhrasetable table, PgfSequenceItor* itor,
+size_t phrasetable_size(PgfPhrasetable table);
+
+PGF_INTERNAL_DECL
+void phrasetable_iter(PgfConcr *concr,
+                      PgfPhrasetable table,
+                      PgfSequenceItor* itor,
+                      PgfMorphoCallback *callback,
                       PgfPhrasetableIds *seq_ids, PgfExn *err);
 
 PGF_INTERNAL_DECL
diff --git a/src/runtime/c/pgf/reader.cxx b/src/runtime/c/pgf/reader.cxx
index 0737888b5..cf939441e 100644
--- a/src/runtime/c/pgf/reader.cxx
+++ b/src/runtime/c/pgf/reader.cxx
@@ -160,7 +160,7 @@ Namespace<V> PgfReader::read_namespace(ref<V> (PgfReader::*read_value)(), size_t
     ref<V> value = (this->*read_value)();
     Namespace<V> right = read_namespace(read_value, len-half-1);
 
-    return Node<V>::new_node(value, left, right);
+    return Node<ref<V>>::new_node(value, left, right);
 }
 
 template<class V>
@@ -576,13 +576,42 @@ ref<PgfSequence> PgfReader::read_seq()
     return seq;
 }
 
-void PgfReader::read_seq_id(ref<ref<PgfSequence>> r)
+ref<Vector<ref<PgfSequence>>> PgfReader::read_seq_ids(object container)
 {
-	size_t seq_id = read_len();
-	ref<PgfSequence> seq = phrasetable_get(concrete->phrasetable, seq_id);
-	if (seq == 0)
-		throw pgf_error("Invalid sequence id");
-	*r = seq;
+    size_t len = read_len();
+    ref<Vector<ref<PgfSequence>>> vec = vector_new<ref<PgfSequence>>(len);
+    for (size_t i = 0; i < len; i++) {
+        size_t seq_id = read_len();
+        ref<PgfSequence> seq = phrasetable_relink(concrete->phrasetable,
+                                                  container, i,
+                                                  seq_id);
+        if (seq == 0)
+            throw pgf_error("Invalid sequence id");
+        *vector_elem(vec,i) = seq;
+    }
+    return vec;
+}
+
+PgfPhrasetable PgfReader::read_phrasetable(size_t len)
+{
+    if (len == 0)
+        return 0;
+
+    PgfPhrasetableEntry value;
+
+    size_t half = len/2;
+    PgfPhrasetable left  = read_phrasetable(half);
+    value.seq = read_seq();
+    value.backrefs = 0;
+    PgfPhrasetable right = read_phrasetable(len-half-1);
+
+    return Node<PgfPhrasetableEntry>::new_node(value, left, right);
+}
+
+PgfPhrasetable PgfReader::read_phrasetable()
+{
+    size_t len = read_len();
+    return read_phrasetable(len);
 }
 
 ref<PgfConcrLincat> PgfReader::read_lincat()
@@ -594,7 +623,7 @@ ref<PgfConcrLincat> PgfReader::read_lincat()
     lincat->n_lindefs = read_len();
     lincat->args = read_vector(&PgfReader::read_parg);
     lincat->res  = read_vector(&PgfReader::read_presult2);
-    lincat->seqs = read_vector(&PgfReader::read_seq_id);
+    lincat->seqs = read_seq_ids(ref<PgfConcrLincat>::tagged(lincat));
     return lincat;
 }
 
@@ -605,7 +634,7 @@ ref<PgfConcrLin> PgfReader::read_lin()
     lin->absfun = namespace_lookup(abstract->funs, &lin->name);
     lin->args = read_vector(&PgfReader::read_parg);
     lin->res  = read_vector(&PgfReader::read_presult2);
-    lin->seqs = read_vector(&PgfReader::read_seq_id);
+    lin->seqs = read_seq_ids(ref<PgfConcrLin>::tagged(lin));
     return lin;
 }
 
@@ -623,7 +652,7 @@ ref<PgfConcr> PgfReader::read_concrete()
     concrete->ref_count    = 1;
     concrete->ref_count_ex = 0;
 	concrete->cflags = read_namespace<PgfFlag>(&PgfReader::read_flag);
-	concrete->phrasetable = read_namespace<PgfSequence>(&PgfReader::read_seq);
+	concrete->phrasetable = read_phrasetable();
 	concrete->lincats = read_namespace<PgfConcrLincat>(&PgfReader::read_lincat);
 	concrete->lins = read_namespace<PgfConcrLin>(&PgfReader::read_lin);
 	concrete->printnames = read_namespace<PgfConcrPrintname>(&PgfReader::read_printname);
diff --git a/src/runtime/c/pgf/reader.h b/src/runtime/c/pgf/reader.h
index 87c678b61..fe5006eb2 100644
--- a/src/runtime/c/pgf/reader.h
+++ b/src/runtime/c/pgf/reader.h
@@ -74,7 +74,9 @@ public:
     ref<PgfPResult> read_presult();
     PgfSymbol read_symbol();
     ref<PgfSequence> read_seq();
-    void read_seq_id(ref<ref<PgfSequence>> r);
+    ref<Vector<ref<PgfSequence>>> read_seq_ids(object container);
+    PgfPhrasetable read_phrasetable(size_t len);
+    PgfPhrasetable read_phrasetable();
     ref<PgfConcrLin> read_lin();
     ref<PgfConcrPrintname> read_printname();
 
diff --git a/src/runtime/c/pgf/writer.cxx b/src/runtime/c/pgf/writer.cxx
index f1293bd18..ecb267c68 100644
--- a/src/runtime/c/pgf/writer.cxx
+++ b/src/runtime/c/pgf/writer.cxx
@@ -418,6 +418,22 @@ void PgfWriter::write_seq(ref<PgfSequence> seq)
     write_vector(ref<Vector<PgfSymbol>>::from_ptr(&seq->syms), &PgfWriter::write_symbol);
 }
 
+void PgfWriter::write_phrasetable(PgfPhrasetable table)
+{
+    write_len(phrasetable_size(table));
+    write_phrasetable_helper(table);
+}
+
+void PgfWriter::write_phrasetable_helper(PgfPhrasetable table)
+{
+    if (table == 0)
+        return;
+
+    write_phrasetable_helper(table->left);
+    write_seq(table->value.seq);
+    write_phrasetable_helper(table->right);
+}
+
 void PgfWriter::write_lincat(ref<PgfConcrLincat> lincat)
 {
     write_name(&lincat->name);
@@ -448,7 +464,7 @@ void PgfWriter::write_concrete(ref<PgfConcr> concr)
 
     write_name(&concr->name);
     write_namespace<PgfFlag>(concr->cflags, &PgfWriter::write_flag);
-	write_namespace<PgfSequence>(concr->phrasetable, &PgfWriter::write_seq);
+	write_phrasetable(concr->phrasetable);
     write_namespace<PgfConcrLincat>(concr->lincats, &PgfWriter::write_lincat);
 	write_namespace<PgfConcrLin>(concr->lins, &PgfWriter::write_lin);
 	write_namespace<PgfConcrPrintname>(concr->printnames, &PgfWriter::write_printname);
diff --git a/src/runtime/c/pgf/writer.h b/src/runtime/c/pgf/writer.h
index 4ee415fdd..1bf7c9370 100644
--- a/src/runtime/c/pgf/writer.h
+++ b/src/runtime/c/pgf/writer.h
@@ -46,6 +46,7 @@ public:
     void write_symbol(PgfSymbol sym);
     void write_seq(ref<PgfSequence> seq);
     void write_seq_id(ref<ref<PgfSequence>> r) { write_len(seq_ids.get(*r)); };
+    void write_phrasetable(PgfPhrasetable table);
     void write_lin(ref<PgfConcrLin> lin);
     void write_printname(ref<PgfConcrPrintname> printname);
 
@@ -56,6 +57,7 @@ public:
 private:
     template<class V>
     void write_namespace_helper(Namespace<V> nmsp, void (PgfWriter::*write_value)(ref<V>));
+    void write_phrasetable_helper(PgfPhrasetable table);
 
     void write_text(ref<ref<PgfText>> r) { write_text(&(**r)); };
     void write_lparam(ref<ref<PgfLParam>> r) { write_lparam(*r); };
diff --git a/src/runtime/haskell/PGF2.hsc b/src/runtime/haskell/PGF2.hsc
index 623167297..ad6300fc4 100644
--- a/src/runtime/haskell/PGF2.hsc
+++ b/src/runtime/haskell/PGF2.hsc
@@ -294,7 +294,7 @@ showPGF p =
                   bracket (wrapSequenceItorCallback (getSequences ref)) freeHaskellFunPtr $ \fptr ->
                   withForeignPtr (c_revision c) $ \c_revision -> do
                     (#poke PgfSequenceItor, fn) itor fptr
-                    withPgfExn "showPGF" (pgf_iter_sequences (a_db p) c_revision itor))
+                    withPgfExn "showPGF" (pgf_iter_sequences (a_db p) c_revision itor nullPtr))
       doc <- readIORef ref
       return (seq_ids, doc)
       where
@@ -303,6 +303,7 @@ showPGF p =
           def <- bracket (pgf_print_sequence_internal seq_id val) free $ \c_text -> do
                      fmap text (peekText c_text)
           modifyIORef ref $ (\doc -> doc $$ def)
+          return 0
 
 -- | The abstract language name is the name of the top-level
 -- abstract module
@@ -570,20 +571,33 @@ unk _ _                                = False
 fullFormLexicon :: Concr -> [(String, [MorphoAnalysis])]
 fullFormLexicon c = unsafePerformIO $ do
   ref <- newIORef []
-  (allocaBytes (#size PgfSequenceItor) $ \itor ->
-   bracket (wrapSequenceItorCallback (getSequences ref)) freeHaskellFunPtr $ \fptr ->
+  (allocaBytes (#size PgfSequenceItor) $ \itor1 ->
+   bracket (wrapSequenceItorCallback (getSequences ref)) freeHaskellFunPtr $ \fptr1 ->
+   allocaBytes (#size PgfMorphoCallback) $ \itor2 ->
+   bracket (wrapMorphoCallback (getMorphology ref)) freeHaskellFunPtr $ \fptr2 ->
    withForeignPtr (c_revision c) $ \c_revision -> do
-     (#poke PgfSequenceItor, fn) itor fptr
-     seq_ids <- withPgfExn "fullFormLexicon" (pgf_iter_sequences (c_db c) c_revision itor)
+     (#poke PgfSequenceItor,   fn) itor1 fptr1
+     (#poke PgfMorphoCallback, fn) itor2 fptr2
+     seq_ids <- withPgfExn "fullFormLexicon" (pgf_iter_sequences (c_db c) c_revision itor1 itor2)
      pgf_release_phrasetable_ids seq_ids)
   fmap reverse (readIORef ref)
   where
-    getSequences ref itor seq_id val exn = do
+    getSequences ref _ seq_id val exn = do
       bracket (pgf_sequence_get_text_internal val) free $ \c_text ->
         if c_text == nullPtr
-          then return ()
-          else do lemma <- peekText c_text
-                  modifyIORef ref $ (\lexicon -> (lemma, []) : lexicon)
+          then return 1
+          else do form <- peekText c_text
+                  case form of
+                    [] -> return 1
+                    _  -> do modifyIORef ref $ (\lexicon -> (form, []) : lexicon)
+                             return 0
+
+    getMorphology ref _ c_name c_field c_prob exn = do
+      name  <- peekText c_name
+      field <- peekText c_field
+      let prob = realToFrac c_prob
+          ann = (name,field,prob)
+      modifyIORef ref (\((form,anns) : lexicon) -> (form,ann:anns) : lexicon)
 
 
 -- | This data type encodes the different outcomes which you could get from the parser.
diff --git a/src/runtime/haskell/PGF2/FFI.hsc b/src/runtime/haskell/PGF2/FFI.hsc
index b4530456f..6c0b26844 100644
--- a/src/runtime/haskell/PGF2/FFI.hsc
+++ b/src/runtime/haskell/PGF2/FFI.hsc
@@ -46,6 +46,7 @@ data PgfLinBuilderIface
 data PgfLinearizationOutputIface
 data PgfGraphvizOptions
 data PgfSequenceItor
+data PgfMorphoCallback
 data PgfPhrasetableIds
 
 type Wrapper a = a -> IO (FunPtr a)
@@ -112,11 +113,15 @@ foreign import ccall pgf_iter_lincats :: Ptr PgfDB -> Ptr Concr -> Ptr PgfItor -
 
 foreign import ccall pgf_iter_lins :: Ptr PgfDB -> Ptr Concr -> Ptr PgfItor -> Ptr PgfExn -> IO ()
 
-type SequenceItorCallback = Ptr PgfSequenceItor -> CSize -> Ptr () -> Ptr PgfExn -> IO ()
+type SequenceItorCallback = Ptr PgfSequenceItor -> CSize -> Ptr () -> Ptr PgfExn -> IO CInt
 
 foreign import ccall "wrapper" wrapSequenceItorCallback :: Wrapper SequenceItorCallback
 
-foreign import ccall pgf_iter_sequences :: Ptr PgfDB -> Ptr Concr -> Ptr PgfSequenceItor -> Ptr PgfExn -> IO (Ptr PgfPhrasetableIds)
+type MorphoCallback = Ptr PgfMorphoCallback -> Ptr PgfText -> Ptr PgfText -> (#type prob_t) -> Ptr PgfExn -> IO ()
+
+foreign import ccall "wrapper" wrapMorphoCallback :: Wrapper MorphoCallback
+
+foreign import ccall pgf_iter_sequences :: Ptr PgfDB -> Ptr Concr -> Ptr PgfSequenceItor -> Ptr PgfMorphoCallback -> Ptr PgfExn -> IO (Ptr PgfPhrasetableIds)
 
 foreign import ccall pgf_get_lincat_counts_internal :: Ptr () -> Ptr CSize -> IO ()