>I have an app that allows users to save their data to an myfilename.CSV. Can anyone tell me how I can make that particular file read only so that they can't make anychanges tothe data once they bring that file up in Excel.?

Try something like this

lnAttributes = 32 + 1 && archive + read only
* 32 = archive, 1 = read only, 2 = hidden, 4 = system
lcFileName = 'test.csv'

declare integer SetFileAttributes in win32api ;
string cFileName, ;
integer nFileAttribute

lnResult = SetFileAttributes(lcFileName, lnAttributes)