rudram,chamakam,rudraikadashini,Lghu Rudram,Maharudram,Atitudram

chanting the whole eleven anuvakams of Srirudram followed by eleven anuvakams of chamakam is called the sadharana rudra japam.

chanting srirudram once followed by the first anuvakam of chamakam, then the whole rudram again followed by the second anuvakam of rudram... thus continuing to chant the rudraprashnam eleven times each time followed by the successive anuvakams of chamakam is called rudraikaadashini

Eleven times rudraikadashini is called Laghu Rudram

Eleven Laghu rudrams constitute a Maharudram

and

Eleven Maharudrams constitue and atirudram..

These are the usual variations in chanting Sri Rudram.. namakam and chamakam..