This centre is not referred to in the Tantric system, which emphasies instead the Ajna as experienced in the middle or the front of the head, nor is it mentioned by Mantak Chia. But it is described by Barbara Brennan, who associates it with the executive will, and thus sees it as the natural counterpart to the forehead centres.  She associates it with the executive will, with practicality and the the bringing into manifestation of ideas formulated through the forehead centres.  If this centre is blocked while one or both forehad centres are open, one may have a lot of good ideas, but have difficulty putting them into practice.

Correspondences:

Spokes/Petals: Tansley - 96.

Associated Psychological states:

Open and Balanced: You are able to express and follow through those ideas generated in the forehead centres with the appropriate action, to enable them to come into manifestation in the material world [Brennan, p.78].

Overactive: You are overly concerned with the practical, to the expense of the visionary or idealistic.

Malfunctioning: You are able to bring things about, but in a distorted way. You may tend to destructive or criminal behaviour [Brennan, p.79]

Blocked: You are unable to bring things about on a practical level. If this centre is blocked while your forehad centres are open, you have a lot of very good, inspiring ideas, but cannot acomplish anything with them [Brennan, p.78].

Chakra balancing

Further notes

In terms of the astrological sequence suggested here,  this center could be associated with the planet Jupiter (which Hienze links to the Ajna centre between the brows) and the sign of Sagittarius, representing expansion and higher learning.  The colour in this instance is sky-blue, the colour of the higher mind.

Kabbalistically, this would be the position of Binah or "Understanding", the highest sefirah in the "Pillar of Severity" (= Governor Channel).  This sefirah preceeds Daat, and is traditionally associated in Hermetic Qabalah with Saturn.  And whilst acknowledging that there may indeed be Saturnian as well as Jovian qualities associated with this Centre, I would prefer to link the macrocosmic Sphere of Saturn with the following, Crown, Chakra.

major and minor Chakras | Notes on Psychological terms

rear chakras ascending		front chakras descending
Crown
Back of Head		upper forehead
		forehead
Mouth of God		Talu/Lalana
Back of Neck		Throat
Base of Neck		Thymic
Shoulder Blades		Heart
Diaphragmatic		Solar Plexus
Door of Life		Navel / Sea of Ch'i
Sacral		Pubic
Coccygeal
Perineum