Compared to built-in code review rules, custom rules are more powerful and require slightly more configuration. A custom rule is created from a template, which in this context means a built-in rule for which you specify one or more parameters that affect the behavior of the rule. You first select a rule template and then specify values for the template's parameters. There is also a severity value that is set and processed exactly as in a built-in rule.
A custom category is a folder for storing custom rules. A custom rule cannot be created unless there is some custom category in which to create it. A custom category is created inside a parent category, which can be either a built-in category, such as Performance or Program Structures, or another custom category.
When you have created a custom category and have added rules to it, the new custom category appears in the software analysis configuration editor, as a new rule category under the analysis domain COBOL Code Review or PL/I Code Review. As with regular rules, you can then select the custom rules that you want to be active in a particular software analysis configuration.