title: Disable edits to a file
body: <p>I created a program in C# which read some lines in a database and store them in a RTF file, after that the file is converted to a another extension of file to be opened by a program. those files are some bills and what i want to do is prevent edits to those bills avoiding problems with clients if ever user make some mistakes.</p>
  
  <p>I tried to go to those file properties and set them as read only but when opened by that ERP, they can still be edited.</p>
  
  <p>Is there a way to prevent other programs/user from editing files?</p>