The shorter drills at Eagle while they will also be used to potentially expand the perifery of the resource, per the news release, they are mainly going to be used to do in-fill drilling.

In-Fill means that holes are drilled between already existing ones.

Example: initial holes could have been drilled on 100 meter spacings and in-fill would be between them resulting in 50 meter spacings. I have experienced situations where even as tight as 25 meter spacings were used.

The in-filling is done to get a more precise image of what is there. ( with valuable resources such as platinum where veins even if very narrow are very valuable, closer spacings are very desirable.) This results in a better confidence of what and amount of resource present. Hence the change in status from inferred to say, proven.