The checking module has two basic services. It can flag unacceptable recognition results without changing them or it can be permitted to modify recognition results using checking module feedback. The available acceptance rules can come from the following:

• Language and/or Vertical dictionaries
• User dictionaries containing precise entries and/or required patterns
• User-written checking functions

These three sources may be combined freely. The checking module and each of its three parts can be enabled or disabled on a per-zone basis. The integrator should try to match the particular parts of the checking module to the contents and recognition modules of individual zones.