There is currently no way to do this without writing custom code. I hear they are trying to incorporate AutoIncrement keys in later versions but not something that is available right this second. So without writing code you are out of luck I am afraid
I don’t recommend you to assign the next id when you get a new record because it could be that another user also gets the same next id if he is on this program at the same time. So, instead of adding your NextID logic on a Post Directive on Ice.UD100.GetNewUD100 method, you better do it on a Pre Directive on Ice.UD100.Update. That will reduce the rist of duplicate key.
I don’t have an epicor 10 where do build an example, but what you have to implement should be something like:
On the UI customization
0. disable Key1
On the BPM Pre UD100.Update
get added record on temporary table ttUD100
get last record on physical table UD100
if no record found assign ttUD100.Key1 = “1”;
if there is a record then assign ttUD100.Key1 = (System.Convert.ToInt32(UD100.Key1) + 1).ToString();