Hi Ramesh,
Can you show me the screen field (screenshot) - of which field you try to validate.
Please refer to the include - MV50AFZ1
This has
FORM USEREXIT_SAVE_DOCUMENT
USEREXIT_SAVE_DOCUMENT_PREPARE.
USEREXIT_MOVE_FIELD_TO_LIPS./ LIKP
These form subroutines will have the Text item ids....You can use the read_text there with salesorder no ... please put breakpoint there and see
Hope this will help you..
Regards,
Venkat