The affix ghañ comes after the verb stṝ 'to cover' when preceded by the preposition pra ; provided that the word so formed does not refer to sacrifice.,
As, शङ्खप्रस्तारः 'a bed of conch'; मणिप्रस्तारः 'strewing of gems'.,
प्रे स्त्रो ऽयज्ञे
Adhyāya 3 · Pāda 3 · Rule 32