Name for the Default Mapping Rule. Must begin with an ASCII alphanumeric or underscore (_) character, and must contain only ASCII alphanumeric, underscore, hash (#), period (.), space, colon (:), at (@), equals (=), and hyphen (-) characters. Cannot be changed after the MAP Default Mapping Rule is created. The following requirement applies only to the Citrix ADC CLI: If the name includes one or more spaces, enclose the name in double or single quotation marks (for example, "add network MapDmr map1 -BRIpv6Prefix 2003::/96"). Default Mapping Rule (DMR) is defined in terms of the IPv6 prefix advertised by one or more BRs, which provide external connectivity. A typical MAP-T CE will install an IPv4 default route using this rule. A BR will use this rule when translating all outside IPv4 source addresses to the IPv6 MAP domain.