PLN Role in ER

Hello all,

Please forgive for my lack of knowledge but I've searched the web as well as the various posts on here and can't find an answer.

I am a nursing student doing a 10week rotation at a small (15 bed) ER in Southern California.

In this particular facility we have a PLN (Paramedic Liason Nurse) he's an RN and he does not take on an assignment, he's used more in a float/MICN/break relief role, from what i've seen. We have several MICNs on shift (not designated, whoever is near the radio answers it first) as well as a designated float RN (typically our 3p-3a RN) so im curious as to what his role is in the ER.

Thanks for all your help.