All Astakvarga based on Rekha and Bindu.
As we know that in any chart, planet placed in any house in any sign has impact on all sign either positive or negative. And in astakvarga we calculate impact on all 8th chart means Lagan chart and 7th physical plant chart.
Suppose in any chart Moon is placed in 9th house in Aries sign in lagan chart. Then in all other chart Moon house may be changed due to we taking lagan reference as placement of planet. For example in above chart Sun is placed in Cancer sign in 12th house in lagan chart. This means when we construct Sun chart then Moon in 10th house in Sun chart in Aries sign. My mean Sign of planet is not change in any Natal chart. So we take Sign has reference to know number of Rekha(positive point) and number of Bindu (negative point).
So Moon in lagan chart either produce 1 Rekha or 1Bindu in lagan chart in each sign. In same ways it produces 1 Rekha or 1Bindu in other 7 chart.
Means 1rekha or 1bindu in each sign in each chart.
So total number will be 8 (rekha +Bindu ) in each sign for a planet in all 8refrence chart.
This collective number of Rekha(positive impact) in each sign is know Bhinnashtka point.
Suppose in our chart Moon has 4 Rakha in Aries sign. So we may told Moon has 4 Binashtaka point in Aries. In simple we say Moon has 4 Astakvarga point in Aries.
So when we told Moon has 4 Bhinnashtka point or Astakvarga point then it’s mean Moon has 4 Rekha in Aries sign and rest is Bindu.
So as we know that total point may be 8. So we may calculate easily that Moon has 4 Rekha and 4 Bindu in Aries sign for our chart.
When we prepare a chart for all planet and Sign by taking number of Rekha in each sign for each planet then it is called Bhinnashtka Varga(Chart) or Simply Astakvarga chart.