propertyName: references a property of the host with the propertyName name.
attr.attributeName: references an attribute of the host with the attributeName name. The initial value is set to the associated directive property. Setting a value in the property updates the attribute on the corresponding HTML element. Using the null value at this level removes the attribute on the HTML element.
style.styleName: links a directive property to a style of the HTML element.
class.className: links a directive property to a class name of the HTML element. If the value is true, the class is added otherwise removed.
eventName: the name of the event to register a method callback on.