Rubble in MC games

[tbridges]

I'm trying to edit some of the PDT values for a MC game. I understand how to adjust most of the settings up or down and how that influences results. But I don't understand how to edit the Rubble percentages. The current value listed in the PDT is 1000.

The PDT help file says: "Rubble Fire Value: this value is used to determine the probability that Indirect Fire and bombing attacks against a Village, Town, City, or Industrial hex will result in Rubble. A file value against the hex of this value will have a 50% chance of creating Rubble in the hex." What does this last sentence mean? How do I change the setting to increase/decrease the chance of Rubble being formed? I tried various settings from "0" to "9999" and none seem to noticeably affect the probability of creating rubble.

Tom Bridges