Is it possible to control visualization of a work item type?

Hi,

is there any way to set a specific role to visualize only some types of work items, and not others.

For example, a role "client" would view only work items of the type "support request". Other work item types (defect, task, etc) would not be visible for "client" role.

How can I achieve that in a same project area? Is it possible?

Thanks in advance for any help!

(Using RTC 3.0)