This is something that I don't think is set into stone on any documents and it really varies with what homeowners decide to do when this time comes (foreclosure). I have seen homes almost emptied (appliances, fixtures, you name it!). It really is a fine line with what people's opinions will be on the subject, simply because if you think about the future homeowners and the bank's ability to resell in it's current condition it will vary due to the condition you leave the home in.
If it were me in the situation, would I take the appliances? Probably. I would def. try to leave at least the outside in as decent shape as possible for the neighbor's sake. So that they don't have an abandoned looking property that lends itself to possible theft and just affects the overall appeal of the neighborhood.
Once again, this is just a matter of deciding how much your appliances, etc. are worth to you and as far as legalities go, I am not aware of any issues with taking your appliances with you when you vacate.
Best of Luck.