Thanks for the quick reply.
Is this an AEM component in its own right? On the Default Components page you posted, it's listed in a separate section (not part of the component list itself). If it is indeed a customizable component, would you happen to know what it's called? Also, are there any specific instructions to get our customized version to appear as the default implementation in the author interface, so that my version is used when authors right-click a component and choose "annotate?"