The idea is kinda to mix for example silver tabby fur with russian white. To layer the silver tab over the russian white and then erase huge parts of the tabby so it's becoming a white cat with silver tabby "blobs" on the fur.
Cats showing such typical domestic fur usually have a white belly. The "tabby part" on the face often paints a turned upside-down V over nose and eyes. Also around the neck the fur mostly shows a "white collar" and while the back then shows the tabby fur again and goes all up to the whole length of the tail. Sometimes there's a white point on the tail or the body is completely white showing no tabby spots. Also the tabby spots can be grey or red and sometimes even blend from grey to red, making the cat a tricolor.
And here some pictures I found on the net to give some impressions:
And I just found out, their official designation is: Domestic Shorthair