FileName$ = OpenFileRequester("","foo.txt","*.txt",0)

If ReadFile(0, FileName$)          ; use ReadFile instead of OpenFile to include read-only files
  BOMformat = ReadStringFormat(0)  ; reads the BOMformat (Unicode, UTF-8, ASCII, ...)
  While Not Eof(0)
    line$ = ReadString(0, BOMformat)
    DoSomethingWithTheLine(Line)
  Wend
  CloseFile(0)
EndIf