The value of option code 4, which defines time servers list. Each IP address is represented in dotted decimal notation format with ';' between them.
Sources for this description
Multiple manufacturers; see the original MIB MIB copies (LibreNMS/Observium Community)Dell MIB copies (LibreNMS/Observium Community)Netdisco MIB archive copiesNETGEAR official product and EOL MIB downloads