I think it might be easier changing the attributes of the files in a folder. The code below does this for C:\test folder.

DECLARE INTEGER SetFileAttributes IN kernel32.dll;
   STRING @ lpFileName,;
   INTEGER dwFileAttributes
   
#DEFINE FILE_ATTRIBUTE_NORMAL    0x0080
#DEFINE FILE_ATTRIBUTE_READONLY  0x0001

SET DEFAULT TO C:\test
lnNumFiles = ADIR(FileList,'*.*')

FOR t = 1 TO lnNumFiles
   =SetFileAttributes(FileList[t,1], FILE_ATTRIBUTE_READONLY)
ENDFOR