面包屑的三种类型 zz
http://en.wikipedia.org/wiki/Breadcrumb_(navigation)
Types of breadcrumbs
There are three types of web breadcrumbs:
* Path: path breadcrumbs are dynamic and show the path that the user has taken to arrive at a page.
* Location: location breadcrumbs are static and show where the page is located in the website hierarchy.
* Attribute: attribute breadcrumbs give information that categorizes the current page.