Vimalaprabha (Sanskrit) means 'Stainless Light Commentary', or 'Dri-med ‘od' (in Tibetan), it is a commentary to the Kalachakra tantra, more specifically, the Laghutantra or Abridged Kalachakra Tantra from Shambhala King Manjushri-Yashas. The Vimalaprabha was written by Shambhala King Pundarika.
This Vimalaprabha commentary, together with the Laghutantra form the basis of the Kalachakra practice as it is currently known and practiced in Tibetan Buddhism, as part of the Vajrayana practices. The Vimalaprabha (Wyl. dri med 'od), translated as Stainless Light or Immaculate Light, is the main commentary on the Kalachakra tantra. Composed by Pundarika, the second Kalkin king of Shambhala, and introduced in Tibet in the 11th century, it is the basis for all Kalachakra commentaries.