if there is a one for one relationship between Development type and Development Type, make a table for the choices even though it would be a small table with only three records in it. And then I would have a relationship and pull in both the development type in the development code from that table.
And alternative would be a hard coded formula to calculate the value of the development code but I don't think it's good practice to do that become because it becomes very obscure how one would add a new drop down choice.
I would not recommend using for rules because they don't working grid edit.
But having said all that and example of a formal role would be this
When development type equals Choice 1
Change the value of development code to Code1