The concepts and terms explained so far, such as process areas, capability levels, and equivalent staging, are common to all CMMI models. However, there are some additional terms that are particularly significant in the CMMI for Services model. Although all are defined in the glossary, they each employ words that can cover a range of possible meanings to users from different backgrounds, and so they merit some additional discussion to ensure that model material that includes these concepts is not misinterpreted.