Object Oriented MXML Components
MXML are just a different way of defining ActionScript classes. Thus, an MXML Component can also make use of ActionScript's Object Orientation.
Inheritance
Extending another component...
<mynamespace:MyComponent ... xmlns:mynamespace="my.package.*" > ... </mynamespace:MyCompontent>
Implements (Interfaces)
An MXML component can also declare itself as implementing one or more interfaces. The implements attribute is used for this.
<mynamespace:MyComponent ... implements="my.package.MyInterface" xmlns:mynamespace="my.package.*" > ... </mynamespace:MyCompontent>
Multiple interfaces may be listed as a comma-delimeted list.