diff --git a/pl/udi.yap b/pl/udi.yap
new file mode 100644
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@@ -0,0 +1,26 @@
+/*************************************************************************
+*									 *
+*	 YAP Prolog 							 *
+*									 *
+*	Yap Prolog was developed at NCCUP - Universidade do Porto	 *
+*									 *
+* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
+*									 *
+**************************************************************************
+*									 *
+* File:		tabling.yap						 *
+* Last rev:	8/2/88							 *
+* mods:									 *
+* comments:	support tabling predicates				 *
+*									 *
+*************************************************************************/
+
+:- meta_predicate udi(:).
+
+/******************
+*     udi/1     *
+******************/
+
+udi(Pred) :-
+   '$new_udi'(rtree, Pred).
+