Although the sequence numbers are incrementing in an ordered list, they may be displayed in a variety of different formats selected by this property.
You can override this on an item-by-item basis and so this property is related to the LI.type property.
The following type values are appropriate for this list type:
1 - Numeric
a - Alphabetical - lower case
A - Alphabetical - upper case
i - Roman numerals - lower case
I - Roman numerals - upper case