The directory associated with the software release to which the system is upgrading. For sets, if the directory starts with a forward slash, it is absolute; otherwise, it is relative to the release root that contains the release files. For gets, the response will be the absolute directory, including the release root and including a leading forward slash. This is cleared following a commit to the release. A set pdu including this attribute must also include attribute tnSwNodeControl; otherwise, the set will be failed back to the network operator.