Python uses whitespace indentation, rather than curly brackets or keywords, to delimit blocks. Godot includes a script editor with auto indentation, syntax highlighting and code completion. The Rockwell scale is a hardness scale based on indentation hardness of a material. Formatting was achieved with capitalization, indentation, and new lines. Changes in indentation serve as the delimiters. Synthetic diamond is the hardest known material, where hardness is defined as resistance to indentation. Tests for indentation hardness are primarily used in engineering and metallurgy fields. Firmness is measured by a foam's indentation force deflection (IFD) rating. Brinelling is the permanent indentation of a hard surface. There are three main types of hardness measurements&colon; "scratch", "indentation", and "rebound". For thin samples indentation depth can be an issue due to substrate effects. Data-structure hierarchy is maintained by outline indentation. Python uses indentation to indicate control structures, so "correct indentation" is required. The following is an example of indentation blocks in Python. Note that in the following list indentation indicates interface inheritance.