Too long for a post Lynn, there are books on the subject! I did my PhD on variegation! Here's the abridged version!
This one looks to be a mutation in one of the anthocyanin genes so that it is turned off in segments. These chimeral plants that are random throughout the rosette are unstable. Propagules from the anthocyanin-containing sections will have anthocyanin, those without anthocyanin not, and a very few will stay variegated. Some very mutable ones will continue to produce variegated segments such as Poco Loco. These are similar to the variegated corn kernels studied by McClintock (jumping gene Nobel Prize winner). They have a more random look to the anthocyanin distribution.
A more stable arrangement occurs in Brillante, in which a whole tissue layer is mutant. These will produce their like. New Rhumba and Laszlo's variegated one are also this type of mutation. The ubiquitous variegated hosta are this type of mutation.
Hope that helps!
Kevin
