Prevent work item type from being assigned erroneous value

Is there a way in the process configuration to prevent a work time type (say a task) from being able to be assigned a complexity (points) which should be reserved (normally) for a story?

For example, if a CSV file contains import definitions for a work item type Story and work item type Task and the fields "Acceptance Test" and "Story Points" (which are custom attributes in our process configuration) are included as follows:

Acceptance Test ... Estimate  Story Points ... Type

In order to...                8 pts            Story

                    1 hour                     Task

The task is imported with an erroneous blank Acceptance Test value and a null or zero Story Points value which appear on the custom tab and are visible from a plan view (Story Points only).

Interestingly, the story is not imported with an erroneous Estimate value. I suspect this might be the case due to the fact that Estimate is not a custom attribute.

Thanks!
Mike