A புறத் திணை in this scheme: one-sided, unrequited love - grouped here rather than in அகம் since it falls outside the mutual love the 5 landscape திணை assume.

கைக்கிளை poems are deliberately rare in the classical corpus - unrequited love wasn't the mutual ideal the 5 landscape திணை describe, so poets and grammarians alike treated it as its own separate case.

A lover pining for someone who does not return the feeling.