Hi:
Behind the scenes of the LIST Data task is PROC PRINT. If you create a TXT file (Listing Destination output), using LIST Data task (PROC PRINT), then you 
cannot wrap text. If you create a TXT file (Listing Destination output), using PROC REPORT code, then you 
can wrap text.
See Example 1 program in this forum posting for an example of PROC REPORT code vs using a format in PROC PRINT:
http://support.sas.com/forums/thread.jspa?messageID=7408ᳰ
If you switch over to the world of ODS (and use ODS RTF, ODS PDF or ODS HTML), you CAN wrap text for those destinations' output files by using the CELLWIDTH style attribute. The CELLWIDTH technique will even work for PROC PRINT -- but ONLY with those 3 destinations (NOT LISTING Destination, therefore, not TXT).
The bottom line is that if you are using the List Data task and sending your output to the LISTING destination (TXT file), then there is no way to force wrapping. You 
can use the FLOW and WIDTH options with PROC REPORT -- but this only works for LISTING.
Perhaps this table will convey the information better. PRINT and List Data Task are the same thing in this table. LISTING destination and TXT file are the same thing:
[pre]
  PROC              DESTINATION      TECHNIQUE   WORK
----------------  ---------------- ------------- ----
PRINT/LIST Data    Listing(TXT)    change format  NO
REPORT             Listing(TXT)    FLOW/WIDTH     YES
REPORT             ODS destination FLOW/WIDTH     NO
REPORT/PRINT       ODS HTML        CELLWIDTH      YES
REPORT/PRINT       ODS RTF         CELLWIDTH      YES
REPORT/PRINT       ODS PDF         CELLWIDTH      YES
REPORT/PRINT       Listing(TXT)    CELLWIDTH      NO
[/pre]
cynthia