This feature isn't implemented. Is that something Mediawiki does?
MediaWiki does not support manually annotating a section, but MediaWiki will automatically divide all html head titles(h1, h2 ...) into a section, so the granularity of a page is relatively small, and conflict will happen rarely, while in Xwiki, only "
1.1" tag will generate a section to edit.
This is a bug. Would you mind creating a JIRA issue for it? (in the
XWiki Platform project - http://jira.xwiki.org)