What do the numbers mean in Strukturbericht notation?

[gaus12777]

I have found about Strukturbericht and got some information.
But I don`t know what these number means.
I heard that Mn_5Ge_3 is a D8_8 type structure.
I already found that D means A_m B_n compound. But I can`t find anywhere what the number mean.

 

[jedishrfu]

I found this reference which shows the various crystal classifications:

https://homepage.univie.ac.at/michael.leitner/lattice/struk/index.html