如何用SPSS编写数据清洗程序？SPSS编程语言有哪些？

*********无条件漏答清洗*******
define !bm(!positional !cmdend).
!do !x !in(!1).
use all.
compute t1=sysmis(!x).
string t2 (a40).
compute t2=''.
if (t1=1) t2='错误A：漏答'.
filter by t1.
list id !x t2.
delete var t1 t2.
!doend.
!end define.

!bm n1 n2 n3 n4 n5 n6.

*********有条件漏答清洗*******

define bk(!positional !tokens(1)/!positional !tokens(1)/arg1=!tokens(1)).
use all.
if (!1=!arg1) t1=missing(!2).
string t2 (a40).
compute t2=''.
if (t1=1) t2='错误A：漏答'.
filter by t1.
list id !2 t2.
delete var t1 t2.
exe.
!end define.
bk n1 n3 arg1=1.
这两个程序如何理解？