One of the Ancient Vedic Hymn in praise of Lord Siva, is Sri Rudram. Various attributes and aspects of Lord Siva are invoked and worshipped. One gets phenominal benefits by chanting Rudram with or without the accompaniment of a Vedic Yajna.
When Sri Rudram is chanted along with Namakam and Chamakam, it is known as Rudraprasna.
Four types of Abhisheka procedures compatible with Vedic Scriptures are Rudram, Ekadasha Rudram, Maha Rudram and Ati Rudram.
Sri Rudram : Reciting the entire 11 Chapters of Namaham and 11 Chapters of Chamakam
Ekadasha Rudram: Reciting the entir 11 Chapters of Namaham 11 times followed by first, Second canto of Chamaham for each Namakam recitation. Also known as Rudraikadasini.
Laghu Rudram : 11 Rudraikadasini makes 1 Laghu Rudram (121 times of recitation)
Maha Rudram : 11 Laghu Rudram makes to one Maha Rudram (1331 times of recitation)
Ati Rudram : 11 Maha Rudram makes to one Ati Rudram (14,641 times of recitation)