Yes, you are right. The below works:

CLOSE all
USE reinreq
m.m_filename = "TestSDF.txt"
set FILTER TO EMPTY(DATE_SENT) .AND. !DELETED()
LOCATE
IF FOUND()
   SET FIELDS GLOBAL
   SET FIELDS TO AGENT_CODE, AGENT_CSR, ACCOUNT=CAST(ACCOUNT AS C(9)), NAME,;
	POLICY=CAST(POLICY AS C(14)), CO_CONTACT, AMOUNTPAID, FAX_MAIL,;
	COMMENTS, REC_DATE, REC_NUM, REC_TYPE,;
	DATE_ENTER
   COPY TO (m.m_filename) TYPE SDF
   SET FIELDS TO
   MODIFY FILE (m.m_filename)
ENDIF

>>I tried that myself Fabio to no avail. It drops the two fields that use CAST() completely. No error, but the resultant file is missing those two fields.
>>
>>
>This works for me
>

>CREATE CURSOR REINREQ (AGENT_CODE N(6),ACCOUNT N(20),POLICY C(25))
>APPEND BLANK
>REPLACE ACCOUNT  WITH 999999999999999
>REPLACE POLICY WITH REPLICATE('D',25)
>LOCATE
>IF FOUND()
>	SET FIELDS GLOBAL
>	SET FIELDS TO AGENT_CODE, ACCOUNT=CAST(ACCOUNT AS C(9));
>,		POLICY=CAST(POLICY AS C(14))
>	BROWSE
>	COPY TO SDFFILE TYPE SDF
>	SET FIELDS TO
>	MODIFY FILE SDFFILE.TXT
>ENDIF
>