I found in the help

3.If you need to retrieve the value of a DDO field,you can always use the Field_Current_Value message. This retrieves the current value of a field from the DDO’s local DDO-Field-Buffer. Note that this is the current value – if a field valuewas changed since it was last found, those changes will be retrieved.The file-buffer will contain the old value of the field – the field valuebefore it was changed. If a field is unchanged, the DDO field value andfile buffer value will be the same. Therefore, if you know that a fieldis unchanged you can use the file buffer to retrieve field values. Ifa field has not been changed, the following two code examples would returnthe same result.

Edgar