Thank you for giving me the opportunity to assist you. I will give the best answer that I can with the information provided.
There are no "standard" codes for box 14, because it is an optional additional information box. Code E in box 12 would mean contributions to a 403B deferred compensation plan.
There are many things that E 10 may stand for--employer reimbursement, state disability, special military pay designation, etc.
You may need to ask your employer for the exact meaning of the code.
Here is a summary of Box 14 and a rehash of what I told you: