This dialog allows you to manage the priority of rules within a chosen rule category. It is the rule priority that defines the order in which multiple rules of the same type are applied when, for example, performing a Design Rule Check. Rule priority simplifies the process of defining and managing rules, the idea being to define general rules that cover broad requirements and then override these with specific rules in specific situations.
It may arise that a design object is covered by more than one rule with the same scope. In this instance, a contention exists. All contentions are resolved by the priority setting. The system goes through the rules from highest to lowest priority and picks the first one whose scope expression(s) match the object(s) being checked.
The dialog is accessed from the PCB Editor, by clicking the Priorities button, at the bottom of the PCB Rules and Constraints Editor dialog. The latter is accessed using the Design » Rules command, from the main menus.
Rule Type - use this drop-down to choose the specific rule type, whose defined rules you wish to manage the priorities for. Note that all rule types are listed, regardless of whether or not rules of a particular type actually exist.
Initially, the dialog will list all rule instances for the rule type that is currently selected in the PCB Rules and Constraints Editor dialog.
Priority Listing - this, the main region of the dialog, presents a list of all currently defined rules of the chosen type. Rules are listed in order of priority, with the highest priority (1) at the top of the list. For each rule, the following read-only information is available:
Priority - a number representing the rule's current priority. The smaller the number, the higher the priority, with 1 being the highest priority.
Enabled - reflects whether the rule is currently enabled (box checked) or disabled (box unchecked).
Name - the name of the rule.
Scope - the scope of the rule. This entry shows the logical query expression (unary rule) or expressions (binary rule) used to target the required objects in the design.
Attributes - the constraints for the rule, along with their defined values.
Increase Priority - click to increase the priority of the selected design rule (where applicable).
Decrease Priority - click to decrease the priority of the selected design rule (where applicable).