Title explains my question. Is there a way to add a 6th key field to a UD table?
My hunch is no, but don’t want to be too definitive. That would change the underlying table identity keys and I can’t imagine the BOs could adapt to that.
The UD10x series tables have a child table with an ‘A’ suffix, that has an additional set of keys. If your scenario is a parent/child table, this might be an option.
Just use UD Column Maintenance and make a Key6_c to your UD Table, it will do the trick 
Wouldn’t that just create a table extension called Key6_c without making it a key field?
If you need more than 4 columns to uniquely identify your record…maybe using the child table would do the job by re-thinking how your data can be segmented.
Adding Key6_c udField is just adding another field no? that field is not flaged as a Key. Unless afterwards you go to SSRS and change the field as a Key field… but I do not think Epicor likes that… 
and besides… like Aaron said, I do not think the BO would deal with this new field…as a key. Maybe it is something to test under a test environment of Epicor ?
Pierre
I have ran into needing something like this too.
Except with Time & Expense entry with entering Weekly Time and the way Epicor attempts to summarize to existing LaborDtl records doesn’t allow me to effectively add a UD field to LaborDtl and then hijack the WeeklyTimeView.MessageText to capture my UD field value on the week and then assign it to the LaborDtl UD field. If everything else but the daily hours are the same Epicor just adds the new entry hours to the existing LaborDtl.
Any way to trick Epicor into thinking a new LaborDtl record is needed?
I’m impressed with the data acrobatics that Epicor does with the WeeklyTimeView but I’m afraid it’s too sophisticated to safely manipulate.