Currently, the only way of organize and filter inside the app units list, is by Ascending or Descending order (Asc is by default) 

I would like a way to create a custom order (for example, if my main building name begin with the letter Z, I want it placed on top of my list instead of my least important building) 

Switching to Descending order place my Z building first, but also reverts the apartment orders (from 999 to 001) so I still would like my order to be

Z001
Z002
Z003
A001
A002
A003