Specifying a validation RMSfile on the Field Description form requires that the data entered into the field be a valid key in another RMSfile. The RMSfile to be used for validation is named in the Validation File field. When the user exits a screen field that has a validation file specified and the screen field contains data, form reads the validation file using the screen field contents as the key value. If there is no such record in the validation file, form displays an error message. If a record is found with a key value equal to the field contents, form saves a copy of that record in an internal buffer.
Form can also display one or more data field values from the record saved by the validation.
To do so, an additional field is created on the data entry screen for each field to be displayed from the saved record. In these fields, the lookup field in the Field Description form gives the data field name in the validation RMSfile that is to be displayed on the screen. Normally, these fields have both Entry Allowed and In Data File set to no . This places a field on the screen, but the screen field does not represent a data field in the current data record. The field is displayed as an underlined field to show that the field value cannot be changed.