You assign it to the ruleset you want it to go with.
So, let's say you have in rule_sets a rule with values 1, default.
And you want that rule_set to have a maxlevel of 65. The values for that in rule_values would be:
1,Character:MaxLevel,65
Now, you have another ruleset with values 2, cavedude.
You want that to have a maxlevel of 75. In rule_values you would have another entry:
2,Character:MaxLevel,75
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