Parent

This is probably the most common hierarchy match that will get used in your templates.  When you use a parent hierarchy match, you essentially saying "find me items whose parent looks like this".  A really common example would be to get the latest three blog posts to show on the homepage.  Here is how you might do it:

{'type':'post','parent':{'type':'feed','url':'/blog'},'count':5,'orderBy':'-publishedAt'}

This will get the newest five posts whose parent is a feed with the url '/blog'.  When you are putting a subobject in the parent field, there are no additional rules.  You can do any kind of match.  A great example of this is grabbing the latest items from EITHER a blog OR a news section.  Here is how you would do that:

{'type':'page','parent':{'type':'content','url':['/blog','/news']},'count':5,'orderBy':'-publishedAt'}

I am now getting the newest five pages with a parent that has '/blog' or '/news' as the url.  Notice that in both my primary query and my subquery I made the types more generic.  It is easy to forget to add the correct types to your query, so remember to pay attention to this.