Final answer:
Dan's secondary suite built above his detached garage without the necessary permits is considered an illegal or unauthorized secondary suite because it has not been constructed in compliance with local building codes and regulations.
Step-by-step explanation:
Since Dan lives in a land-use district that permits secondary suites and he decides to build one above his detached garage without obtaining the necessary municipal building permits, the type of secondary suite Dan has can be considered an illegal suite or unauthorized secondary suite. Even though the district permits secondary suites, the construction of such a unit typically requires a building permit to ensure that the suite meets the local building codes and regulations for safety, design, and occupancy standards. By not obtaining these permits, Dan's suite would likely not be recognized by the municipality as a legal dwelling unit, which could lead to possible penalties, and it may require additional measures to bring it up to code if discovered by local authorities.