Classes must be named according to Zend Framework's naming conventions.

The brace should always be written on the line underneath the class name.

Every class must have a documentation block that conforms to the PHPDocumentor standard.

All code in a class must be indented with four spaces.

Only one class is permitted in each PHP file.

Placing additional code in class files is permitted but discouraged. In such files, two blank lines must separate the class from any additional PHP code in the class file.

The following is an example of an acceptable class declaration:

/**
 * Documentation Block Here
 */
class SampleClass
{
    // all contents of class
    // must be indented four spaces
}

Classes that extend other classes or which implement interfaces should declare their dependencies on the same line when possible.

class SampleClass extends FooAbstract implements BarInterface
{
}

If as a result of such declarations, the line length exceeds the maximum line length, break the line before the "extends" and/or "implements" keywords, and pad those lines by one indentation level.

class SampleClass
    extends FooAbstract
    implements BarInterface
{
}

If the class implements multiple interfaces and the declaration exceeds the maximum line length, break after each comma separating the interfaces, and indent the interface names such that they align.

class SampleClass
    implements BarInterface,
               BazInterface
{
}

Member variables must be named according to Zend Framework's variable naming conventions.

Any variables declared in a class must be listed at the top of the class, above the declaration of any methods.

The var construct is not permitted. Member variables always declare their visibility by using one of the private, protected, or public modifiers. Giving access to member variables directly by declaring them as public is permitted but discouraged in favor of accessor methods (set & get).