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?
What are DRY, KISS, SOLID, etc. classified as?
design patterns;terminology;methodology
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  developmentKISS: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