Please excuse my dust while I revamp this section
The English Spotting, or Broken, gene creates a more or less random pattern of white spots or patches over the rabbit's color. Usually the patterns are very smooth-edged.
There are two genes in this color group: En and en, with En being dominant. Enen will cause normal spotting as in a broken color rabbit. The colored portions of the fur are patched or blanketed with white in between. Ideally, a broken patterned rabbit should have a balanced marking on its nose, ears should be fully colored, the front feet should be white, and the colored portion should be more than 10% but not exceed 50% coverage.
The English Spotting gene has partial dominance- it is always expressed if present. Rabbits cannot carry the broken gene- they are either broken/Charlie, or not. Two solids cannot produce a broken.
"Charlie" is the term for a rabbit with less than 10% color. There are two types of Charlies- genetic Charlies (EnEn) and false Charlies (Enen but with less than 10% color- technically just a poorly patterned broken). Charlies typically lack nose spots. Genetic Charlies (EnEn) will only ever be able to contribute an En gene, so will always throw broken kits. It’s generally not a good practice to breed two broken rabbits together as this can result in genetic Charlies. There is some belief that Charlies may be more prone to digestive issues such as megacolon. Charlies are also not recognized in many breeds. However, they can be useful to a breeding program- if you are willing to wait for a second generation, the resulting Charlies could be bred with a solid colored rabbit, resulting in all brokens.
I've hard that the term "Charlie" comes from Charlie Chaplin, because the abbreviated butterfly that most Charlies have.
Because the REW (Ruby Eyed White) gene (cc) masks all color and pattern, it's impossible to tell by just looking at a REW rabbit whether it is a solid (enen), broken (Enen), or Charlie (EnEn). You may be able to determine whether the rabbit expresses the En gene by the pedigree/parents, but otherwise the best way to determine is to test breed to a solid (enen) rabbit.
There are several modifiers that can affect a broken pattern. Booted is one of the more common modifiers, and results in a rabbit with more than 50% color. Booted rabbits often have the appearance of wearing white "boots," hence the name "booted." Booted rabbits typically have white on the feet, throat, and forehead.