Symbolic constants, mapped to integers using the PHP define function, are preferred to numeric or string constants;
Filenames should match class names; for example, the SectionEditorAction class is in the file SectionEditorAction.inc.php;
Class names and variables should be capitalized as follows: Class names use CamelCase, and instances use lowerCamelCase. For example, instances of a class MyClass could be called $myClass;
Whenever possible and logical, the variable name should match the class name: For example, $myClass is preferred to an arbitrary name like $x;
Class names and source code filenames should be descriptive and unique;
Output should be restricted as much as possible to Smarty templates. A valid situation in which PHP code should output a response is when HTTP headers are necessary;
import(...) calls should be kept as localized as possible;