Zend Framework standardizes on a class naming convention whereby the names of the classes directly map to the directories in which they are stored. The root level directory of Zend Framework's standard library is the "Zend/" directory, whereas the root level directory of Zend Framework's extras library is the "ZendX/" directory. All Zend Framework classes are stored hierarchically under these root directories..
Class names may only contain alphanumeric characters. Numbers are permitted
in class names but are discouraged in most cases. Underscores are only permitted in
place of the path separator; the filename "
must map to the class name "
If a class name is comprised of more than one word, the first letter of each new
word must be capitalized. Successive capitalized letters are not allowed, e.g.
a class "Zend_PDF" is not allowed while "
These conventions define a pseudo-namespace mechanism for Zend Framework. Zend Framework will adopt the PHP namespace feature when it becomes available and is feasible for our developers to use in their applications.
See the class names in the standard and extras libraries for examples of this classname convention.
Important: Code that must be deployed alongside Zend Framework libraries but is not part of the standard or extras libraries (e.g. application code or libraries that are not distributed by Zend) must never start with "Zend_" or "ZendX_".