---
title:  Including and excluding targets and features
blurb:  A reference of how to use targets and features in more detail than that
        provided in the Help Structure section.
layout: template-logo-medium
---
<%= md_links %>
<%= md_images %>


<%= current_page.data.title %>
==============================

<%= current_page.data.blurb %>


Why include and exclude?
------------------------

Although _Middlemac_ is an excellent tool for developing single-target Apple
Help Books, it really shines when you want to develop multiple versions of
help books for multiple versions of your application.

Delivering a help system tailored _specifically_ for the version of the
application that it belongs to will increase user satisfaction by allowing them
to focus on the aspects of the help that’s applicable to them. No one wants to
attempt to solve a problem and then learn, during troubleshooting, that some
fancy feature is only available in some other version of your application.

You want to promote other versions of your application, certainly. Multiple
targets allows you appropriately place upsell messages without distracting
your users. It also allows you to avoid upselling the users who are already
using your premium or top-level version.

Maybe your application is available on your website and also the Mac App Store?
In this case there are certainly going to be feature differences. You web
version uses _Sparkle_ for updates, but the MAS version doesn’t. Your MAS
version requires users to authorize writing to user directories because of
sandboxing, whereas your web-distributed version does not.

Make your help files as polished as your applications, and users will be happy
and delighted without even really knowing why!


Include and Exclude Parts of Pages
----------------------------------

In the simplest case you have help page that is present for all versions of your
help book, but some of the content will be different for different targets and
features. You can re-visit the [`target_name?`][targets] example and the
[`target_feature?`][features] example to review how to show and hide specific
content on each page.

Limit Images to Particular Targets and Features
-----------------------------------------------

Don't forget that the [`image_tag` helper][helpers_ext_ref] can be used with
parameters to limit images to certain targets and features, too.


Include and Exclude Entire Pages
--------------------------------

In the case of wanting to hide or show entire pages based on target or feature,
you’ve also seen the `target` and `exclude` [front matter][frontmatter] keys.
When used, you have excellent control over whether entire pages are visible or
not.