Hi Fernando,
use the below sample code to get the run time header text.
write the below code in USEREXIT_SAVE_DOCUMENT_PREPARE.
DATA : begin of wa_tline,
tdformat like tline-tdformat,
tdline like tline-tdline,
end of wa_tline.
data it_tline like table of wa_tline.
data temp_vbeln(70) type c.
temp_vbeln = xvbak-vbeln.
CALL FUNCTION 'READ_TEXT'
EXPORTING
* CLIENT = SY-MANDT
id = 'Z053'
language = 'E'
name = temp_vbeln
object = 'VBBK'
* ARCHIVE_HANDLE = 0
* LOCAL_CAT = ' '
* IMPORTING
* HEADER =
tables
lines = IT_TLINE
* EXCEPTIONS
* ID = 1
* LANGUAGE = 2
* NAME = 3
* NOT_FOUND = 4
* OBJECT = 5
* REFERENCE_CHECK = 6
* WRONG_ACCESS_TO_ARCHIVE = 7
* OTHERS = 8
.
IF sy-subrc <> 0.
* MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
* WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
Thanks,
Sumanth P