Introduce an option to change the character which follows the list level symbol. By default this is a Tab character, however, they can be the following:
- Tab
- Space
- Nothing (none following character)

In OOXML, this is described using the 'suff' element.
In MS Word, this setting could be changed by selecting the bullet/number of the list item -> Context Menu -> Adjust List Indents -> Follow number with:.