Holes or spaces (avakāśa; avakasa) created upon the surface of a wall of a fortress or castle is called ākaśajananī (akasajanani). In fact, while building the castle, such holes were created upon the external wall so that the insiders of the castle could keep an eye on the enemies and throw rocks or fiery arms at the enemies. Like ghatākāśa (ghatakasa) and patākākaśa (patakasa) , the word ākāśa (akasa) has been used here in the sense of ‘avakāśa’ ( open space). Citing scriptural sources, the commentator Nīlakaṇṭha(Nilakantha) has shown that the guards who were placed at these holes upon the wall, were called ākāśarakṣī (akasharakshi; guard of the open space)
In Mahābharata (Mahabharata), there is a mention of the construction of pragaṇdī (pragandi) or sitting arrangement. This was to be created so that the soldiers and generals, sitting there, could observe the movements of the enemy through the holes.