I am not sure the intent of this foreign key, however it seems problematic as we can't tie it to a single category

To test:
1 - Add an authorised value for Asort1:
    Authorised value: MONKEY
    Description: Capuchin
2 - Add an authroised value for LOC:
    Authorised value: MONKEY
    Description: Spider
3 - Put an illrequest in the DB:
    INSERT INTO illrequests (branchcode,status,status_alias) VALUES ('CPL','REQUEST_TEST','MONKEY')
4 - Delete one of the authorised values above
5 - Check the DB:
    SELECT status_alias FROM illrequests WHERE status = 'REQUEST_TEST'
6 - Note the status is nulled by deletion of unrelated authroised value