drop down list

[karlson]

its possible to create a drop down list like this:
1. A
1.a
2.b
3.c
2. B
1.a
2.b

etc.?

 

[Swathi]

I think it is not possible with one drop down list.
But you can take two drop down lists. In the first drop down place 1.A,2.B
etc., in the second drop down place 1.a,2.b,3.c, etc., based on the value
selected in drop down1 using filter.