Customer Service (Level 4, Advanced) - Works with clients and customers (that is, any individuals who use or receive the services or products that your work produces, including the general public, individuals who work in the agency, other agencies, or organizations outside the Government) to assess their needs, provide information or assistance, resolve their problems, or satisfy their expectations; know about available products and services; and am committed to providing quality products and services. This experience must demonstrate proficiency in the following: Experience providing analysis, technical, and programming expertise in the development and maintenance of operating system software and data center operations support within one or more of the following platforms/operating systems: mainframe, PC/Windows, and/or Linux/UNIX on multiple hardware platforms.