Wap2 phones seem to me like an evolution of i-mode.  Wap2 phones can view content that is known as xhtml mobile profile.  In much the same way as chtml (used for i-mode content) xhtml mobile profile is little more than simplified xhtml.  xhtml is simply a stricter, cleaned up version of html, in fact a replacement for html.

There are some subtle differences between wap2 browsers and ordinary web browsers on PCs however.  A wap2 phone does not talk directly to a web server.  Instead it connects through a wap2 gateway, which is a type of web proxy.  The are some adjustments to the TCP stack (wap1 used UDP) so make it more suitable for a wireless environment.  However this is between the phone and the gateway, and so should not be visible to the web server that supplies content.

Some useful sites for xhtml mobile authoring are here and here.

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