42. X means the information extraction system has the capability; X* means the information extraction system has the ability as long as the training corpus can accommodate the required training data; ? Shows that the systems can has the ability in somewhat degree; * means that the extraction pattern itself doesn’t show the ability, but the overall system has the capability. Nested_ data Free Resilient Permuta_tions Missing items Multi-slot Single-slot Semi Struc_ ture Name X X X ? X X ? ? X X X X ROAD_ RUNNER X X X AutoSlog X X X X X X X BYU Onto ? X* X X X X X WHISK ? X X X X X SRV ? X X X X X RAPIER X X * X X X STALKER X* X X X X X SoftMealy X X X WIEN