Some adapters have state information that must be preserved between HTTP requests. For example, TDataSetAdapter has a mode property. HTML forms that modify TDataSetAdapter datasets include the mode property value as a hidden field. When the HTML form is submitted, the mode property value will be included in the HTTP request. When executing an action TDataSetAdapter extracts the mode property value from the HTTP request and updates it's mode property. ListHiddenRecordFields may call AddAdapterModeHiddenField depending on the flags returned by GetHiddenFieldOptions. 

GetHiddenFieldOptions 

ListHiddenRecordFields 

AddAdapterModeHiddenField 

GetAdapterHiddenFields