The program sees the commas as the value dividers. Thus, you cannot use commas in the combo box list of values.
If you have a list of:
you would enter this as ABC,DEF,GHI
Ex1. If you want to have JK,L as a value, (this will not work)
then when you enter:
ABC,DEF,GHI,JK,L then JK and L are seen as two different values.
Ex2 , If you enter ABC,DEF,GHI,"JK,L" you get: