Enabled design constraint rules are applied to the current board design through a range of mechanisms, such as live Online Design Rule Checking, the batch Design Rule Checker or selectively run from the PCB Rules and Violations panel. 

Violations of those constraint Rules – where the specified and scoped limits are exceeded – are indicated through board graphics, panel entries and reports. With the introduction of a new Rules Editor in Altium Designer 21, violations of these rules are now displayed in the Rules Editor itself.

And as a bonus, violations can be inspected, analyzed, and corrected while the Rules Editor is open, thanks to its design document (rather than dialog) format.