The resource entity tag as defined in http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.11 Entity tags are also added as 'ETag' response headers to requests that do not use the 'depth' parameter.
[optional] [readonly]
last_modified_date
datetime
The date the resource was last modified.
[optional] [readonly]
last_software_updated_date
datetime
The date when the software on the node was last updated.
