Form understanding is a fundamental problem in deep-web crawling, data integration, (object) search, and data extraction. Moreover, web sites are increasingly used on devices or in contexts not anticipated by their developers. Form understanding can significantly improve accessibility of forms and support assistive technologies, e.g., for mobile use (such as keyboard layouts, gestures, and auto-completion appropriate to the type of field).
It can also prove a valuable tool in developing form-based web applications, e.g., for automated testing or validation.
In all these cases, a form model needs to describe the types and relations of form fields in terms of a common schema as well as the logical structure of the form grouping semantically related fields.
In DIADEM form understanding is provided by OPAL.