diff --git a/packages/curation/curation_summary_tree.pro b/packages/curation/curation_summary_tree.pro
new file mode 100644
index 0000000..f646121
--- /dev/null
+++ b/packages/curation/curation_summary_tree.pro
@@ -0,0 +1,86 @@
+:- module(curation_summary_tree,
+	  [
+	   write_xlinks_for/1
+	   ]).
+
+:- use_module(curation_db).
+:- use_module(bio(ontol_db)).
+
+/*
+
+  e.g.
+
+  reg and negreg some (synth and has_out some x)
+
+  reg
+    negreg
+      synth
+        has_in
+          x
+        has_out [s/-/reg]
+          y
+  
+*/
+
+class_xlink(C,EList) :-
+        genus(C,Genus),
+        differentium(C,Prop,Filler),
+        !,
+        L1=[
+            node(C),
+            node(C/Prop),
+            label(C/Prop, Prop),
+            node(Filler,Filler),
+            label(C,Genus),
+            edge(Filler,C/Prop),
+            edge(C/Prop,C)],
+        findall(L2,class_xlink(Filler,L2),LoLs),
+        flatten([L1,LoLs],EList).
+
+class_xlink(C,[node(C)]) :- !.
+
+/*
+class_xlink(C,EList) :-
+        \+ genus(C,_),
+        parent(C,_R,P),
+        class_xlink(P,EList).
+*/
+
+write_xlinks_for(C) :-
+        class_xlink(C,L),
+        write_xlinks(L).
+
+
+write_xlinks(L_u) :-
+        sort(L_u,L),
+        debug(xlinks,' L=~w',[L]),
+        findall(N,member(node(N),L),Nodes),
+        debug(xlinks,' Nodes=~w',[Nodes]),
+        findall(N,(member(N,Nodes),
+                   \+ member(edge(N,_),L)),
+                Roots),
+        debug(xlinks,'Roots=~w',[Roots]),
+        forall(member(Root,Roots),
+               write_xlinks(Root,[' '],L)).
+
+write_xlinks(N,D,L) :-
+        writetabs(D),
+        writenode(N,L),
+        nl,
+        forall(member(edge(Ch,N),L),
+               write_xlinks(Ch,[' '|D],L)).
+
+writetabs(D) :- maplist(write,D).
+
+writenode(N,EL) :-
+        member(label(N,N2),EL),
+        !,
+        writenode(N2,EL).
+writenode(N,_) :-
+        class(N,Label),
+        !,
+        write(Label).
+writenode(N,_) :-
+        write(N).
+
+