Defines the <oper> format:
0 Long alphanumeric format (up to 16 characters) (default)
1 Short alphanumeric format (up to 8 characters)
2 Numeric
Note1:
If <index> is given but <oper> is left out, entry is deleted.
If <oper> is given but <index> is left out, <oper> is put in the next free location.
If only <format> is given, the format of the <oper> in the read command is changed.
Note2:
User is prevented from editing index No. 0. This index is reserved for the HPLMN record and can not be
modified.
When entering a new item with an <index> to a full list, the Module deletes the last item, stores the new
item in the requested entry, and shifts the rest of the list down.
When entering a new item without an <index> to a full list, the Module replaces the last entry with the new
item.