This read-write enumeration configures the CDMA modem's roaming preference, letting an admin restrict it to home(2) networks only, extend it to affiliated(3) partner networks, or allow any(4) network. An admin controls this to manage cost and service-quality tradeoffs, since restricting to home(2) avoids potentially costlier or lower-quality roaming service, while any(4) maximizes coverage at the risk of roaming charges. For example, an admin managing cellular-backup routers on a fixed data plan might set this to home(2) to prevent unexpected roaming charges if a device drifts to the edge of home-network coverage.