The Seba library treats Central Channel in 3 passages, across 1 author (including Coleman, Graham).
the right and left channels are said to loop around the central channel (avadhuti), forming knots (rtsa-mdud) which obstruct the flow of subtle energy into the central channel.
This passage provides the canonical structural definition of the central channel as the axial conduit obstructed by lateral-channel knots at the five cakras, establishing the physiological basis for tantric soteriology.
, The Tibetan Book of the Dead (Penguin Classics), 2005thesis
when the practices of the perfection stage of meditation are applied, the knots which block their combined movement through the energy centres (Skt. cakra) located on the central energy channel
This passage demonstrates that the central channel is the target of perfection-stage practice, arguing that dissolving the cakra-knots allows vital energy and subtle mind to flow through it, reversing the dispersal caused by past-action energies.
, The Tibetan Book of the Dead (Penguin Classics), 2005thesis
Calm abiding is a meditative technique common to the entire Buddhist tradition, characterised by a stabilisation of attention on an internal object of observation conjoined with the calming of external distractions to the mind.
Though not addressing the central channel directly, this entry on calm abiding contextualises the foundational meditative preparation through which perfection-stage practices — including central-channel work — become accessible.
, The Tibetan Book of the Dead (Penguin Classics), 2005aside