The echo flag is used to alter the value returned by the adapter's fields. When this flag is set, the adapter's fields retrieves their value from the HTTP request. When this flag is clear, the adapter's fields retrieve their current value. Typically, this flag is set after an error occurs while executing an adapter action. Setting this flag results in generated HTML that displays values entered by the end-user. This allows the end-user to make corrections and resubmit the form. 

SetEchoActionFieldValues 

GetEchoActionFieldValues