Managers can specify logical bridge domains as many times as needed without effecting the current box configuration using this object. Setting this object to a new value is stored in a local buffer and the changes are not recorded in the nonvolatile memory. The new value is copied into lBDomainMembership and becomes effective when portGroupAction is set to doUpdate and the updating process successfully upgrades the logical bridge domains. A logical bridge domain is expressed using a shorthand that says what learning domains are members of it. An examples of a specification is: (1,3,5) (2-4) Commas separate items in a list of learning domains. Hyphens are short-hand for specifying a range of numbers. Learning domain numbers are specified in decimal. A logical bridge domain will read back in a form equivalent to the form written. It may not read back exactly as written. Without a management set, the default logical bridge domain (i.e., domain number 1) contains all learning domains. The other logical bridge domains are empty sets. A logical bridge domain is created by specifying what learning domains are members of it. Specified learning domains are deleted from the old logical bridge domain and added to the new logical bridge domain. Deletion and addition of the learning domains are atomic across the SNMP messages. Learning domains left out in the specification will automatically join the default logical bridge domain. Reconfiguring logical bridge domains is an expensive operation. Therefore the manager should not change the configuration very often.