Example .hgignore regarding whole directories

[Harry Putnam]

I wasn't clear from a light (partial) reading of 

    `Mercurial: The Definitive Guide'

What all works in `.hgignore'.

There is a very light discussion in:
  file-names-and-pattern-matching.html

But it was not clear about how directories might be included or what
impart it would have.

The 2 comments there, do not help much either.

Can directories be listed in `.hgignore' with the impact that
everything beneath is ignored.

If that is possible can I see some examples of the syntax?

I'd prefer regular expressions but `glob' would be good too.

When ignoring file/directory names... is the slash (/) part of what
mercurial sees, and can therefore be part of the regex?