Definition #1: "Index files in path"

By far the most frequently used definition, here parent menu items have a link whose href attribute points to a default file in any (non-root) folder in the path leading to the current page, including in the folder containing the current page itself.

For example, where the green boxes indicate the Parent items that were demonstrated in the Video

Definition #2: "Any File in Path"

Parent menu items have a link whose href attribute points to any file in any (non-root) folder in the path leading to the current page, excluding the folder of the current page itself. This definition would most likely be useful only when paired with definition #3 (as it is in definition #5), and would rarely be used by itself.

Definition #3: "File without querystring"

This is for the situation when the current page has a querystring, for example theFile.php?sku=fruit.. Its parent menu item will have a link whose href attribute points to the current file but without any querystring, so in this example: theFile.php.

Definition #3 is unlikely to be useful by itself, but rather when used in combination with the other options, as in definitions #4 and #5.