Is something like DRY a design pattern, a methodology, or something in between? They do not have specific implementations that could neccessarily be demonstrated(even if you can easily demonstrate a case NOT using something like KISS... see The Daily WTF for a plethora of examples), nor do they fully explain a development process like a methodology generally would. Where does that leave these types of "rule of thumb"'s?
According to Wikipedia it is a principle of software development.

In fact, Wikipedia refers to all of them as principles:

DRY:


  In software engineering, Don't Repeat
  Yourself (DRY) or Duplication is Evil
  (DIE) is a principle of software
  development


KISS:


  KISS is an acronym for the design
  principle "Keep it simple, Stupid!".


SOLID:


  The principles when applied together
  intends to make it more likely that a
  programmer will create a system that is easy to maintain and extend over time

