There should be another type of premise for premises that don't fit the main 3 types.
The current three premises are sufficient, as they cover all three possibilities of response: support, opposition, and neutral additions or thoughts.
Taxation is robbery
If robbery is to take property by force, this is true. However, if someone were to reclaim property that rightfully belongs to them by force, that would also be robbery (though just). Robbery has unjust connotations, so this definition may not be accurate, or robbery may sometimes be justified.