Controlling the content of chunks

Would it be possible to create different types of chunks.

e.g. In order to maintain the desired feel resulting from a template layout, the original designer may wish images to always be in the same physical locations on the generated pages (and perhaps always be the same dimensions too) and for only certain areas to contain text.

Despite wanting a consistant design layout there may, for instance, be a requirement to showcase new product images regularly or just to keep a constantly changing fresh feel to the website and to do this the designer wants the editors to be able to regularly change the images in the placeholders provided without diluting his design.

With different types of chunks the designer would be able to specify that only images, text or flash etc could be in any particular location but the editors would be able to change the content (ie swap one image for another or change a body of text to some different text but not be able to insert text where a picture once was).

You can use Template Variables for this
http://modxcms.com/template-variables.html