(!) 03.01: Use spaces instead of tab characters for indentation. The recommendation is two space characters for each level of indentation (four for Python code).

(!) 03.02: Comment your code using Doxygen-style formatting. Read the Doxygen documentation.

(!) 03.03: Provide appropriate error handling.

(!) 03.04: Use speaking and consistent variable names and other identifiers.

(!) 03.05: Enclose code blocks in braces after all flow control statements, even in one-line constructs.

(+) 03.06: Discuss your design decisions with other developers in an early stage of your project.

(+) 03.07: Keep methods and functions overseeable. Split long code segments into functions, use refactoring for "spaghetti code".

(+) 03.08: Put concatenated boolean expressions in parentheses.

(+) 03.10: Avoid long lines. 80-100 characters for a line of code should be enough. Split longer lines into several statements or split them up into several lines using one level of indentation.

(+) 03.11: Avoid redundancy in class data storage as far as possible.

(+) 03.12: Use "return" only at the end of methods or functions in order to gain a better control of resource management.