diff --git a/H/threads.h b/H/threads.h
new file mode 100644
index 000000000..6d4001d63
--- /dev/null
+++ b/H/threads.h
@@ -0,0 +1,12 @@
+typedef struct{
+  UInt		    ssize;
+  UInt		    tsize;
+  int		   (*cancel)(int thread);
+} thread_attr;
+
+Int STD_PROTO(Yap_thread_self,(void));
+Int STD_PROTO(Yap_thread_create_engine,(thread_attr *));
+Int STD_PROTO(Yap_thread_attach_engine,(int));
+Int STD_PROTO(Yap_thread_detach_engine,(int));
+Int STD_PROTO(Yap_thread_destroy_engine,(int));
+