Thanks
Xuan Kong Da Gua is whole system of selecting auspicious date for a given person.
Probably it requires a day or two training to get the basics of the method.
XKDG section in the calculator is rather directed to pple who know the basics.
In a big shortcut, you compare two pillars with each other and check if their Da Gua is supportive.
Method is based on hexagrams and numbers connected with them.
Most important factor is that a given day you choose must support the birth year of a specified person.
But there's much more stuff, many factors, like sum-to-ten, hexagram families, branch conflicts, etc. I think it's not the place to explain everything
it's not as broad as BaZi though.
The overall effect is a green tick that appears when we compare person's birth chart with a selected date
meaning that the date is auspicious
