How it is linked to the menu

The report is inserted into the menu through a funtion in lib.php called

port_advancedgrading_extend_navigation_module

This can be found in this file

https://github.com/marcusgreen/moodle-report_advancedgrading/blob/main/lib.php#L42

It includes a switch case block like this

case 'rubric':
$url = new moodle_url('/report/advancedgrading/rubric.php', array('id' => $cm->course, 'modid' => $cm->id));
$navigation->add(get_string('rubricgrades', 'report_advancedgrading'), $url, navigation_node::TYPE_SETTING, null,
        'rubricgrades');
break;
case 'rubref':
$url = new moodle_url('/report/advancedgrading/rubref.php', array('id' => $cm->course, 'modid' => $cm->id));
$navigation->add(get_string('rubricgrades', 'report_advancedgrading'), $url, navigation_node::TYPE_SETTING, null,
        'rubrefgrades');
break;
            

        etc etc

It could be extended in the future by adding new cases which would hock the report into the menu system