Something thatâ?Ts used in an expression to manipulate objects such as + (plus), - (minus), * (multiply), and / (divide). You can also use operators to do comparisons,such as with <, >, and &&.

XAJAX uses XML as a transport for data between the webpage and server, and you don't write your own javascript data handlers to manipulate the data received from the server. Instead you use a php class and built in javascript methods, a combination that works very similiar to the HTML_AJAX_Action class and haSerializer combo. XAJAX is designed for simplicity and ease of use.
HTML_AJAX allows for multiple transmission types for your ajax data - such as urlencoding, json, phpserialized, plain text, with others planned, and has a system you can use to write your own serializers to meet your specific needs. HTML_AJAX has a class to help generate javascript (HTML_AJAX_Helper) similiar to ruby on rail's javascript helper (although it isn't complete), and an action system similiar to XAJAX's "action pump" that allows you to avoid writing javascript data handlers if you desire.
But it also has the ability to write your own data handling routines, automatically register classes and methods using a server "proxy" script, do different types of callbacks including grabbing remote urls, choose between sync and async requests, has iframe xmlhttprequest emulation fallback capabilities for users with old browsers or disabled activeX, and is in active development with more features planned (see the Road Map for details)
HTML_AJAX has additional features such as client pooling and priority queues for more advanced users, and even a javascript utility class. Although you can use HTML_AJAX the same way you use XAJAX, the additional features make it more robust, extensible and flexible. And it is a pear package, you can use the pear installer to both install and keep it up to date.
If you're asking which is "better" - as with most php scripts it's a matter of taste and need. Do you need a quick, simple ajax solution? Or do you want something that's flexible, extensible, and looking to incorporate even more great features? It depends on the project, you as a writer, and your future plans.

Mobility: it is the efficient movement of people and goods that is seen as beneficial or as they key aim of policy. This is much wiser than a traffic focus because at least it helps move attention to more efficient ways of moving people and goods. This would put a high priority on collective modes of transport (eg buses, rail).

Accessibility or an 'access focus': In this perspective it is the ability to REACH opportunities that is beneficial, not movement itself. In remote rural contexts gaining access to services, goods and contacts will often require a lot of mobility. However, in many urban contexts accessibility might involve very short trips. And in places like suburban USA policy to enhance accessibility might actually require that we reduce traffic or even reduce the need to travel (or reduce mobility).

A new scope for a local variable is introduced in the toplevel, a class (module) definition, a method defintion. In a procedure block a new scope is introduced but you can access to a local variable outside the block.

The scope in a block is special because a local variable should be localized in Thread and Proc objects.

while, until, and for are control structures and the scope is shared with the outside of these structures. loop is a method and the appended block introduces a new scope.

Tabnav it's so far the easiest way to build tabbed navigation .