4. Keep your code (mostly) human readable.
Intentionally obscured code is not allowed in the directory under any circumstances. Unfortunately, many people use such methods to try and hide malicious code. WordPress is intended for anyone to be able to learn from code, edit it, and adapt it. Making code non-human readable, either by hiding it or using obscure naming conventions, forces future developers to face an unnecessary hurdle. Minified code may be used, however the unminified versions should be included whenever possible. Using p,a,c,k,e,r or uglify is to be avoided.