Under maintenance and evolution: The four categories and the concepts that influence the maintenance process. One of them is People. and under people there are $3$ categories that influnce the maintenance. These three are: $1-$ Maintenance Organization

This is the organization that maintains the product$($s$).$

Include managers and engineers.

$2-$ Client Organization

A client organization uses the maintained system.

Has a clear relationship with the maintenance organization.

The said relationship is described in the Service$-$level Agreement $($SLA$).$

Include customers and users.