Board Thread:Support Requests - Getting Technical/@comment-28870704-20160804193139/@comment-1757994-20160804223631

Possible? Yes. Standard wikitext? No. Even more so, because MediaWiki decimal outlining (which just uses standard HTML ) doesn't use dotted notation. 
 * 1) First item
 * 2) Second item
 * 3) First sub-item
 * 4) Second sub-item
 * 5) Third item
 * 1) First item
 * 2) Second item
 * 3) First sub-item
 * 4) Second sub-item
 * 5) Third item

You'd have to use raw XML-style tags and custom Collapsible elements, probably divs.