Thanks for your inquiry. The text line starts with “A, B, ?, C.” is not list item. LoadOptions.AllowTrailingWhitespaceForListItems property allows to specify how numbered list items are recognized when document is imported from plain text format.
If set to true, lists recognition algorithm allows list numbers to end with either dot or whitespace character.
If this option is set to false then the list item is only recognized as such if the leading number is ending with dot “.” symbol.
Could you please share some more detail about your use case? We will then provide you more information on this along with code.