As verse 24 of Vijnabhairav Tantra says:
Bhairava says: Para devi or Highest Sakti who is of the nature of visarga goes on (ceaselessly) expressing herself upward (urdhve) (from the centre of the body to dvàdashànta or a distance of twelve fingers) in the form of exhalation (pràna) and downward (from dvàdashànta to the centre of the body) in the form of inhalation (jiva or apana). By steady fixation of the mind at the two places of their origin (viz., centre of the body in the case of pràna) and dvàdashànta in the case of apàna), there is the situation of plenitude (bharitàsthiti, which is the state of paràSakti or nature of Bhairava).
Visargatma - Who is of the nature of visarga. The word visarga means letting go, projection or creation, i.e. who is creative. The creative function of the Divine includes two movements-outward and inward or centrifugal and centripetal. In living beings, the outward or centrifugal movement is represented by expiration or exhalation; the inward or centripetal movement is represented by inspiration or inhalation. Parā or parā devī or Parā Sakti is designated as Visargātmā, because it is by this rhythm of centrifugal and centripetal movement that she carries on the play of life whether in the macrocosm or the microcosm. This movement is known as uccāra or spandana or ceaseless throb of Parādevi. In Sanskrit, visarga is represented by two points or dots one above the other. One point in this case is dvàdashànta where prāña ends and the other is the centre of the body where apāna ends. It is because of these two points also that Parasakti is known as visargatma.
Dvàdashànta-literally meaning 'end of twelve' indicates the point at a distance of 12 fingers from the tip of the nose in the outer space where expiration arising from the centre of the human body, and passing through the throat and the nose ends. This is known as bàhya dvàdashànta or the external dvàdashànta.
As its presence is known which is 12 fingers away from the tip of the nose. But can anyone tell in which direction? Can anyone affirm the pic, I've concluded Black dot as Dvàdashànta. [