9. The system of claim 8 , wherein the processor is further configured to: apply the second wrapper to each page in the at least other domain in the plurality of domains to extract second additional training data; combine the first training string with the additional second training data to generate a second target string; search other domains in the plurality of domains to determine if any of the other domains comprises portions of the second target string; and create a third wrapper for at least another of the other domains in the plurality of domains from the second target string.
8. A system for automatically constructing wrappers across a plurality of domains, the system comprising: a memory; and a processor coupled to the memory, the processor configured to: create a first wrapper in a first domain using a first set of training data, the first set of training data created from a subset of documents in the first domain; apply the first wrapper to each page in the first domain to extract additional training data; combine the first set of training data with the additional training data to generate a first target string; search other domains in the plurality of domains to determine if any of the other domains comprises documents having portions of the first target string; and create a second wrapper for at least one of the other domains in the plurality of domains from the first target string.