On Bebo, they use SNML (Social Network Markup Language) for application development.

For example:

Code:
<sn:editor>
This is text inside the editor.
<sn:editor-heading>This is the heading</sn:editor-heading>
</sn:editor>
Output:

Which will then output XHTML on the browser.

I contacted Bebo, I asked how SNML (Social Network Markup Language) implemented.

Reply from Bebo:
A java based HTML ==> SAX parser (when a tag is recognized)

Can you please explain how that work when tag is recognized and then convert to XHTML?