[MikeyB (Michael)]

From the BinTel website (more up to date than Meade's own US corporate site!):

Advanced f/10 Coma Free Optics: The LX200-ACF was designed by Meade's top optical engineers to perform just like a Ritchey-Chrétien telescope . The Ritchey-Chrétien, or RC optical design, is well known to discerning astrophotographers and is the telescope optical design in many of the leading professional observatories of the world. The LX200-ACF is the perfect platform for the demanding researcher and imaging enthusiast delivering star images free of coma right to the edge of the field. Meade's industry leading techniques in figuring large aspheric corrector plates allowed Meade's engineers to reduce astigmatism and eliminates diffraction spikes in the new LX200-ACF compared to the traditional RC design.

and

Optical Design: Advanced Coma Free Aplanatic Cassegrain

While the top of the range RCX400 becomes the LX400-ACF.