Taken from the Multimarkdown Users Guide (thanks to @MultiMarkdown on Twitter for pointing it out)
[Some Text][]
will link to a header named “Some Text”
e.g.
### Some Text ###
An optional label of your choosing to help disambiguate cases where multiple headers have the same title:
### Overview [MultiMarkdownOverview] ##
This allows you to use [MultiMarkdownOverview] to refer to this section specifically, and not another section named Overview. This works with atx- or settext-style headers.
If you have already defined an anchor using the same id that is used by a header, then the defined anchor takes precedence.
In addition to headers within the document, you can provide labels for images and tables which can then be used for cross-references as well.