The man page for XF86Config says that it supports discrete values but it generates an error. The commented out lines below break and the uncommented versions work: HorizSync 37.5 - 63.7 # HorizSync 37.5, 37.88, 37.90, 46.875, 48.08, 56.48, 60.023, 63.7 VertRefresh 60-86.906 # VertRefresh 60, 60.317, 70, 70.069, 72.187, 72.81, 75, 86.906 I have attached the resulting output for using discrete values to bug 21631 (attachment 6112 [details]).
XF86Config is the config file for XFree86-Servers-3.3.6. You've filed this bug against XFree86 (4.0.2), and are saying it is a bug with XFree86 4. While this may be true, more likely you've just put the data in the wrong config file. XFree86's config file is XF86Config-4. Can you please clarify what version you're using, perhaps attach the config file, and your XServer output logs?
I am not seeing this after upgrading to XFree86 4.0.2.