If the `threshold' parameter is provided and 0, the `acceleration' parameter will be used in the exponent of a more natural and continuous formula, giving precise control for slow motion but big reach for fast motion, and a progressive transition for motions in between. Recommended `acceleration' value in this case is 3/2 to 2, but not limited to that range.
If the server supports the XFree86-Misc extension, or the XKB extension, then a parameter of 'rate' is accepted and should be followed by zero, one or two numeric values. The first specifies the delay before autorepeat starts and the second specifies the repeat rate. In the case that the server supports the XKB extension, the delay is the number of milliseconds before autorepeat starts, and the rate is the number of repeats per second. If the rate or delay is not given, it will be set to the default value.
These settings will be reset to default values when you log out.
Note that not all X implementations are guaranteed to honor all of these options.