What type of appraisal is designed to validate the continuance of previous ratings?

The type of appraisal designed specifically to validate the continuance of previous ratings is the Sustainment Appraisal. This appraisal focuses on confirming that an organization's capabilities remain consistent over time and that they still meet the established standards previously determined during earlier appraisals. Sustainment Appraisals are particularly important for organizations that want to maintain their ratings as they continue to implement and benefit from process improvements.

In contrast, an Initial Appraisal is meant for organizations seeking their first capability rating, while a Reassessment Appraisal is typically conducted to determine whether an organization has improved or changed its process performance since the last appraisal. A Comprehensive Appraisal encompasses a full evaluation of an organization's processes and performance, but it is not specifically aimed at validating existing ratings. Thus, the key focus of the Sustainment Appraisal makes it the correct choice for this context.