provides a means for subsetting and extending XHTML
a feature needed for extending XHTML's reach onto emerging platforms.
Modularization of XHTML will make it easier to combine with markup tags
for things like vector graphics, multimedia, math, electronic
commerce and more. Content providers will find it easier to
produce content for a wide range of platforms, with better
assurances as to how the content is rendered.
The modular design reflects the realization that a
one-size-fits-all approach will no longer work in a world where
browsers vary enormously in their capabilities. A browser in a
cellphone can't offer the same experience as a top of the range
multimedia desktop machine. The cellphone doesn't even have the
memory to load the page designed for the desktop browser.