Template:Subpage/Doc

creates a link to a subpage of the current page.

Subpages are regular wiki pages.

But their name is the same as their parent page with some additional material on the end, separated by a slash "/". For instance "Template:Link/Doc" is a subpage of "Template:Link".

You can create a link to a subpage with square brackets by starting it with a slash.

For instance, on a page called "Meetings" you might have:
 * /2011-02-11
 * /2011-03-17

The links will appear with the slash in their name, which is somewhat distracting: /2011-02-11

You can clean that up by providing an explicit link text: 2011-02-11 But that's repetitive and difficult to read with longer subpage names.

Instead you can use undefined The link doesn't show with a slash.

Finally, if you want, you can give an explicit link text: undefined