Pagination rules can be applied to entire publications as well as individual sections and subsections. Rules are inherited by child sections from parent publications and by subsections from parent sections. Inherited rules can also be overridden, or, rules can be created on sections only and not set at the publication level at all.
The Defined At column displays where the rules are inherited from. In the below example, the 'I Section' is selected in the Tree, and the Defined At column on the Pagination Rules tab shows that the rules are defined at the 'I Publication' level.
Rules that are applied at lower levels take precedence over rules applied at higher levels. So, if you have applied a rule at publication level, it is inherited to sections and subsections, but rules applied at section or subsection levels take precedence over the inherited rule.
It is possible to edit the action parameter of an inherited rule. A complete rule group can also be overridden manually in cases where you want to change the rule conditions or rules in general.
For information on how to edit and/or override inherited rules, refer to the Editing Pagination Rules topic here.