The understanding makes on the surface text can be shown in different levels

Copyright information: Taken from "PASBio: predicate-argument structures for event extraction in molecular biology"BMC Bioinformatics 2004;5():155-155.Published online 19 Oct 2004PMCID:PMC535924.Copyright © 2004 Wattarujeekrit et al; licensee BioMed Central Ltd. Syntactic categories level gives a syntactical class for each constituent of the sentence. Syntactic relations level describes syntactical function of each constituent of the sentence to predicate of the sentence. Argument categories level offers the semantic concept for each constituent of the sentence. Predicate-argument relation level helps in understanding the semantic role played by each constituent or argument related to its predicate.