在form中的调用函数：
/: PERFORM GET_BSTNK_TEXT IN PROGRAM Zxxx
/: USING &VBDKR-VBELN&
/: CHANGING &BSTNK&
/: ENDPERFORM
在程序中实现：
*-----------------------------------------------------------------------
* GET_BSTNK_TEXT
*-----------------------------------------------------------------------
FORM GET_BSTNK_TEXT TABLES IN_TAB STRUCTURE ITCSY
OUT_TAB STRUCTURE ITCSY.
DATA: tmp_vbeln LIKE vbfa-vbelv.
* read country key from in table
READ TABLE IN_TAB WITH KEY 'VBDKR-VBELN'.
IF SY-SUBRC = 0.
TMP_VALUE = IN_TAB-VALUE.
tmp_vbeln = TMP_VALUE.
ENDIF.
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_INPUT'
EXPORTING
input = tmp_vbeln
IMPORTING
output = tmp_vbeln.
SELECT SINGLE * FROM vbfa WHERE vbeln = tmp_vbeln
AND vbtyp_v = 'B'.
SELECT SINGLE * FROM VBAK WHERE vbeln = VBFA-VBELV
AND auart = 'ZQT'.
IF SY-SUBRC = 0.
READ TABLE OUT_TAB WITH KEY 'BSTNK'.
IF SY-SUBRC = 0.
WRITE VBAK-BSTNK TO OUT_TAB-VALUE LEFT-JUSTIFIED.
MODIFY OUT_TAB INDEX SY-TABIX.
ENDIF.
ENDIF.
ENDFORM.
