Upcoming Keeneland meet - "star" preference system

[oakorchard]

The Keeneland on-line condition book says that Keeneland utilizes the "star" prefernce system for their entries. Can anyone on here give me the simple version of that? How is it different from "zero dates" given at other tracks?

Using the Keeneland star system, is there an advantage to getting your horse on the grounds or papers in the racing office by a certain date?

Thanks much!