Pls help to understand this routine program

Question

Pls help to understand this routine program written in transformation level for a field.
Data a Type /bic/oizsnote_2.
Data: l_len type i,
      l_time type i.
Move source_fields-zztdline+60(60) TO a.
l_len = STRLEN(a).
DO l_len TIMES.
IF a+l_time(1) CN
',<>?/:;"''ABCDEFGHIJKLMNOPQTRSTUVWXYZ abcdefghijklmnopqrstuvwxyz!%^&' & '*' & "()__+=12346567890'
a+l_time(1) = '~'.
Endif.
l_time = l_time + 1.      
enddo.
replace all occurrences of '~' in a with space.
Result = a.
not having much exposure in ABAP programming.
Raj

Answer 1

In addition to the above to posts..
HI Raj,
Your routine is used to remove the invalid characters.
  IF  A+l_time(1)  CN
A is a Char which contains the data .*
  I_time is used for iteration(itu2019ll check each char by char in a word/Sentence).
*CN u2013 Contains not
,?/:;"''ABCDEFGHIJKLMNOPQTRSTUVWXYZ abcdefghijklmnopqrstuvwxyz!%^&' & '*' & "()__+=12346567890.
These are the Valid chars and numbers which will be accepted by BW system, System will throw an error only when load receives a char which is not there in the above. And that char will be treated as a Invalid Char.
A+l_time(1) = '~'.
What ever the special/Invalid char appears in the load apart from the above mentioned, system will convert  them to u2018~u2019
REPLACE ALL OCCURRENCES OF '~' IN a WITH space.
   CONDENSE A.
System will replace all the ~ with space, then condenses the space.
You can do this using RSKC transaction instead of going for routine.