The front matter in my website’s source files can contain a number of different keyed values. An attempt to list them:

Key Usage
date Date for generated HTML page
gallery At bottom of page generate a thumbnail gallery
icon Image to use in links to page which include a picture
image Image to display at top of page
layout Layout to use for page
list At top of page generate a 2-column table of key value pairs
metadata HTML metadata to inject into generated HTML page
resources List of resources to copy for page
tags Tags for this page
title Title for this page

There are defaults for some of these keys: so title defaults to the prettified filename, aspect to the parent page’s aspect.