diff --git a/index.md b/index.md
index e9fb43d..a2531c5 100644
--- a/index.md
+++ b/index.md
@@ -92,11 +92,43 @@ All options are optional, unless otherwise indicated.
 
 ## Customization
 
-The following options can be specified at the heading level via `data-toc-*` attributes.
+### Headings
+
+By default, the plugin chooses the top-level navigation items by searching for headings at the first heading level, then works its way down (`<h1>`, then `<h2>`, etc.) It will stop when it finds the first set of headings where more than one exists at that level. For example:
+
+```html
+<h1>The title</h1>
+<h2>Some sub-title</h2>
+...
+<h3>Section 1</h3>
+<h4>Subsection A</h4>
+...
+<h4>Subsection B</h4>
+...
+<h3>Section 2</h3>
+```
+
+The plugin would see there's only one `<h1>`, then that there's only one `<h2>`, then stop when it sees there's more than one `<h3>`. The identified level becomes the top-level navigation items in the Table of Contents, and any headings under those (the `<h4>`s in this case) would be the second-level navigation.
+
+This behavior can be customized with the `$scope` [option](#options). That jQuery object can be created with one or more selectors to force certain headings to be used.
+
+In the above example, let's say that you wanted the navigation to only contain the Subsections. You could pass:
+
+```javascript
+Toc.init({
+  $scope: $("h4")
+  // ...
+});
+```
+
+and the resulting Table of Contents would only contain:
+
+> * Subsection A
+> * Subsection B
 
 ### Displayed text
 
-By default, Bootstrap TOC will use the text from the heading element in the table of contents. If you want to customize what is displayed, add a `data-toc-text` attribute with the desired text. For example:
+By default, Bootstrap TOC will use the text from the heading element in the table of contents. If you want to customize what is displayed, add a `data-toc-text` attribute to the heading with the desired text. For example:
 
 ```html
 <h2 data-toc-text="Short text">Longer text</h2>
@@ -106,7 +138,7 @@ displays "Longer text" as the heading, but "Short text" in the sidebar.
 
 ### Skipping
 
-To prevent a particular heading from being added to the table of contents, add a `data-toc-skip` [boolean attribute](https://www.w3.org/TR/2008/WD-html5-20080610/semantics.html#boolean).
+To prevent a particular heading from being added to the table of contents, add a `data-toc-skip` [boolean attribute](https://www.w3.org/TR/2008/WD-html5-20080610/semantics.html#boolean) to the heading.
 
 ```html
 <h2 data-toc-skip>Some heading you don't want in the nav</h2>