I have come across a number of mentions of MultiMarkdown\'s support for internal links / named anchors but I am unable to find a single example of how to actually do it.
In standard Markdown, place an anchor where you want to link to and refer to it on the same page by [link text](#abcd).
(This uses name= and not id=, for reasons explained in this answer.)
Remote references can use [link text](http://...#abcd) of course.
This works like a dream, provided you have control over the source and target texts. The anchor can even appear in a heading, thus:
### A Heading in this SO entry!
produces:
and we can even link to it so:
and we can even [link](#head1234) to it so:
(On SO, the link doesn't work because the anchor is stripped.)