#### Bug, feature request, or proposal: Proposal / Question #### What is the expected behavior? What is the scope of the cdk? #### What is the current behavior? CDK works fine! My question is: what is the scope of the CDK? In special: will the [overlays from core](https://github.com/angular/material2/tree/master/src/lib/core/overlay) be added to the CDK? Also on a11y: there seems to be some overlap between [core a11y](https://github.com/angular/material2/tree/master/src/lib/core/a11y) and [cdk a11y](https://github.com/angular/material2/tree/master/src/cdk/a11y) #### What is the use-case or motivation for changing an existing behavior? I am asking because some of the features in core seem so generic that they can be shared and re-used through CDK. #### What are the steps to reproduce? #### Which versions of Angular, Material, OS, TypeScript, browsers are affected? #### Is there anything else we should know?